OK, I think the disconnect here between Max and I is in what we mean by overpowered. Max seems to be using the word overpowered in an absolute sense. Anything that will KO a character in one shot is overpowered. Feel free to correct me on that, Max. That's just how I'm reading your side.
What I mean by not overpowered is that Magic is comparable to other alternatives for doing that same thing. That it is powerful, but it is balanced compared to other powerful things PC's can do. For any given effect, look at all the ways of doing it. In this case that effect is to knock someone out with stun damage. If the total benefit minus the total cost is significantly different for one particular option, its unbalanced. I generally use BP for comparison because its the one place that hardware (costs money) and magic (costs Karma) can be compared.
Take the emotitoy as the most obvious example. It provides a +6 to social rolls for 600 nuyen. So the benefit and the cost are pretty straight forward.
BP/bonus point = .02
Empathy Software on its own costs 2100 for rating 6 but you also need a commlink and OS to run it on. So a Novatech Airware, IRIS Orb and rank 3 Empathy 'ware costs a total of 2,850.
BP/point = .16
An Adept with Magic 3 can get three levels of Kinesics. The Adept Quality and the magic score cost a total of 25 BP. Kinesics eats half of that.
BP/Point=4.16
Glamour provides a similar +3 at 15 BP.
BP/point=5
Vomerovasal Organ provides a +2 for 10 BP but also provides a +3 to sense rolls based on smell and has several drawbacks. As a GM I'd say that pretty much anywhere outdoors in seattle smells bad enough to provide penalties. So the power fails outside and the character has to wear a mask.
BP/point = about 5
Tailored Pheromones cost 15,000 per level and .2 Essence/level.
BP/Point=3
Essence/Point=.2
Enhanced Pheromone Receptors bioware gives up to a +2, has less downside than the Vomeronasal Organ and still provides the perception bonus. It costs 15,000 nuyen and .1 Essence.
BP/Point=1.5
Ess/Point=.05
When you break it down that way, its pretty clear which one of these things is unbalanced. The bioware may be cheaper by a factor of two but the Empathy Software in any form is off by a factor of 30. The Emotitoy is cheaper by a factor of 250. That's unbalanced.
With the combat example that we've already beaten to death, mage damage is cleary not off by a factor of 30. A character starting with Magic 6 and 10 spells is 105 BP into being a Mage (discounting other attributes and skills) and has more or less given up on cyberwear entirely. So let's call the base cost for that stunbolt 10.5 BP. It does as much damage as a Stick'n'shock round (give or take a DV point or two per hit) on average. It also inflicts a point or two on the caster per shot. The Mage must use 100% natural line of sight. Also remember that everything that improves Magic costs Karma. Gunslingers can get better with nothing but money.
Compare that to 52,500 nuyen in guns, specialied ammo, targeting bonuses, cyberwear and systems that cut through environmental factors like smoke, darkness and range.
Or compare it to 52,500 in drones with weapon mounts and their software.
Or take any two spells on your Mage and compare to this contact:
Seattle Ancients Connection 5 Loyalty 6 (+4 size, +4 area of influence, +1 access to magic) 20 BP total, 14 modified Connection
Magic may still come out a little better (except when facing down the Ancients) or it may not but it doesn't come out to be radically more effective compared to its cost: BP, Karma and avoiding cyberware.