I have no idea why you're trying to compare it to sustaining foci, as that's a completely ridiculous and horribly inefficient method to do anything.
Because we were talking about a buff-build with a lot of buff-spells, and you then called Quickening karma-intensive. So I pointed out that compared to a Sustaining Focus version of the same build, Quickening is far less karma-intensive. And if you want to compare it to other characters, we can do that too: 6 karma for a Quickened Increased Attribute, vs 128k nuyen (~64 karma) for +4 Agi, 6 karma vs ~19.5 for +3 Reaction, or 12 karma vs ~142.5 for +3 Reaction and +3d6 Initiative, which is by far outmatched by +4 Reaction & +Xd6+2X Initiative. Also the only way to get an extra +4 defense through Intuition. So while Armor is silly, for the rest you're far cheaper off karma-wise compared to the street sams. So a Quickened build gets it quite easily.
However, I do still believe Quickening comes with risk and a price. But unless you handle it well, and I strongly recommend houseruling it for that purpose, then the only ways to keep it balanced involve either destroying the character or destroying any other tactical magical option, because suddenly wards are so common that you can forget about astral scouting and material links and the sustaining foci peeps have to constantly recast their spells.
...Okay, sure, if you're comparing what this guy is doing with Quickening to a completely nonviable build involving 11 Sustaining Focuses, then it is much less karma-intensive...
Why you make that comparison, I do not know, but whatever you say, man.
As for the other options you listed, those things all have the benefit of being largely unnoticeable, and cannot be easily negated, unlike Quickening. An adept with Improved Reflexes has those permanently and that cannot be taken away. A street sam with wires just needs to watch out for cyberware scanners. Quickening is a quick and relatively cheap way to get those perks, but it has significantly more drawbacks and gets a lot more attention.
As for wards, they actually are incredibly common. A ward is cheap. A single magician with Magic 6 can ward an area of 300 cubic meters. It takes him one day's work to do, and only needs to be renewed every couple of weeks, or with a karma expenditure, it lasts forever. Any run against any organization capable of having a Magician on staff, or who hires any kind of astral security, should have wards in place. It is the most basic form of magical security.
And to the OP, I actually think your main problem is that you're missing a number of important rules, either getting things wrong or ignoring certain rules altogether.
We've got a PC that took Priority D in attributes, spread out evenly (so very average stats for the race, like 3s/4s for human).
Priority D is 14 attribute points. Over 8 attributes, that divides into 1.75 points each. So at the most even distribution, he'd have six attributes at 3, and two at 2. To get an even 3 across the board would require Priority C, and to get any 4s without having 2s would require Priority B.
He started with MAG 7 (from exceptional attribute positive quality), and with 11 spells he eventually quickens; armor, combat sense, increase reflexes and all 8 increase attribute spells. He spent his first 13 karma to get Initiate Grade 1 (quickening metamagic) and his next 11 karma to sustain all 11 of those spells (spending 1 karma each). He spent plenty of time (and edge) during the character's downtime to keep recasting these spells before quickening (to maximize hits), which comes to (say) roughly 7 hits per spell (on Force 7 to Force 10 spells).
I'm extremely curious how this character survived enough runs to earn 24 karma. Even assuming you're generous with the karma rewards, that takes 4 runs, and this guy would have been completely worthless prior to getting all these spells set up.
After this 24 karma, this character already has the trappings of uber sauce, being close to (or at) augmented attribute maximums (natural +4) for all 8 stats, and nice armor/defense/initiative. And thus far, the PC appears to be reasonably safe from losing these spells (and the karma invested) from dispelling and astral intersections.
Augmented maximum is +4. It doesn't care what your natural attribute is, the maximum you can augment any attribute by is +4. I have a feeling you're letting this guy augment by a lot more than that, since with his Priority D, he should only have 6s and 7s in every attribute if he's got 7 hits on those spells. The extra hits don't do him any good, as Increase [Attribute] specifically states that additional hits above the augmented maximum are ignored.
And you're definitely wrong about astral intersections, but we'll get to that in a second.
The dispeller's dice pools seem to be around 12-15 dice (if they even have counterspelling, which many don't seem to have) vs. the PC's 15-18 dice (MAG 7, Force 7 to 10, +1 karma/quickening). With the PC's edge added in, he has been able to keep things running. Add the fact that mages are supposed to be rare to begin with, and its not like awakened NPCs are going to be showing up every fight to dispell (presuming they even have counterspelling). And I'm not trying to go out of my way to take this PCs benefits away. I like the concept of quickening.
Sounds about right.
For astral intersections, I'm assuming Force 6 or Force 7 wards would be considered fairly decent against starting characters. Those would have 12 or 14 dice, vs. the PC's 17 dice (MAG 7 + 10 CHA). The PC has been able to handle this, and toss in edge if it gets close.
And here is a clear indication that your player is ignoring some important rules. First and foremost, there's no way in hell this guy has Charisma 10 at Priority D Attributes. Only way that works is if he's got five attributes at 2, two more at 3, a natural Charisma of 6, and +4 from his Increase Charisma spell. If you allowed him to get +7 Charisma from the spell, you are not following the rules correctly.
Secondly, if he's trying to pass through a ward, he rolls Magic + Charisma [Astral] vs Force*2, and he needs 1 net hit per spell he's bringing with him. That means 11 net hits on 14 dice. Even with you allowing him to have +7 Charisma, that's still 11 net hits on 17 dice. That'd be hard to pull off unopposed, let alone against 12 to 14 dice opposed.
As for an Astral Intersection, he's not rolling his Magic + Charisma against that unless he's dual natured at the time. His spells, however, roll their Force *2. They don't even get his Magic or the karma he spent on them; those things are specific to dispelling. So every ward he tries to cross this way would trigger 11 dice rolls against the Force*2 of the ward.
Now let's fast-forward well beyond the karma we have now to when the PC is a high level initiate and has (say) a MAG rating of 11 and a spellcasting pool of 25 or better. So this mage now recasts and requickens all these spells at higher force with more hits, making it that much less likely for them to be dispelled or disrupted... and giving very large boosts to armor/defense/initiative.
I'm certainly not saying this PC is better than everything else, but I'm struck by the many things this guy has, and it just smacks of being too good in too many areas.
Are you experiencing any of this?
Getting from Magic 7 to Magic 11 would cost 190 karma, not counting the fact he'd need to initiate at least 4 times first. And even with higher spellcasting ability, his attributes aren't getting better than his current rating +4. The hits based spells could get better, but I seriously doubt this guy is going to survive to see 190 karma.