Diagnostics doesn't give you smartlink and it can't allow you to jump-in. Making a complex form to handle these tasks gives them a powerful and necessary niche for TMs.
Yes, +dice is boring, but the entire game revolves around that. Its not even overpowered. You make it sound like TMs are already going to step all over the physical combatants if they're allowed to have as many dice as them without any of the other benefits, like high str to stack armor, high dodge, and high meat world initiative.
Okay, here. How balanced is it that a decker can cut his arm off and get a fully custom cyber arm with 9 agi? Are we to assume that if a TM is able to keep up with a decker they also need to cyber up and take a hit to resonance just to be able to shoot a gun? There aren't enough attribute points and skill points for TMs to make good physical combatants. To give them tools to help even the odds isn't unbalanced, but it does give them more options. Which TMs desperately need.
Yes, the Machine sprite doesn't give you a Smart link. You can wear one in your glasses like everyone else who isn't cybered up, until you're connected enough with the matrix to get an echo for it. Namely the Resonance Program Echo.
But the current core version does suck. Which is why I think it should scale with your Submersion grade. Every grade you have, you get another program. They're small bonuses but they get to add up. Possibly something along the lines of getting datachips or something that could load another program in your biodeck after getting the submersion for a certain period of time before they burn out or something?
Even if you make it a CF for every single skill, you're still not going to at all get anywhere. A Technomancer can start off with at most, Five free CFs. Then they have to spend 4 karma per CF after that.
One of the two biggest issues with a Technomancer is the fact that they have a very high Karma consumption to begin with. If everything a TM does ends up costing more and more karma, Its not going to go very well at all for TMs.
+dice is more than just boring. And the entire game doesn't just revolve around that. It revolves around identities of the characters. We've got the thing that gives us +dice to skills already as technomancers. They're called Machine Sprites. At most, for skills, the most we'd need to develop after that is a single +dice CF, but it still wouldn't be all that great at all.
Not because it would make the TM overpowered or something, but because ultimately, It would just become a karma tax for playing a TM and ultimately doesn't add to their identity of a runner. They just become that guy who can increase his skills a bit. Such hoopla.
Verses a Technomancer who spends all of his nuyen and time working on his gear, upgrading it, enhancing it, so that when he uses his machine sprites on it, it preforms a helluva lot of enhanced functions. Like a Ballistic mask with Vision Enhancements, A smartlink, even a miniature microphone or something. Then he takes a machine sprite and enhances it... Suddenly you're getting a guy who could be in the Crying masks, and possibly feared because how good he is when he's got his mask on.
Basically what I'm saying is No. A Technomancer doesn't need to cut off his arm for a 9 agi gun arm to keep up. And we don't need a lot of uninspired things to try and help a Technomancer dogidly attempt to keep up in physical combat by attempting to pretend we can do what every else can. (CFs to try and add a few extra skill dice after taking the sustaining penalties.)
I've been working on finding somethings a Technomancer could do while in combat, while still maintaining a high Biodeck stats. Using a melee skill + Intuition you can get a +3 to hit on your next attack against a target. Or using con + cha you can pretend to be hurt to the point that you're no longer a threat and the enemies ignore you so you can shoot them in the back. or Perform + Cha. After making a touch attack, you can use Will vs Will to do Cha + Net hits in stun damage to a spririt (This requires a martial art.)
Honestly, IMHO its things like this the technomancer needs more. Things that don't use karma, but brings the mental stats into physical combat. Yes Mages will be able to use it too. Or even faces. Most of the time Mages will elect lighting bolts to the face however.
Another possibility is expanding the martial arts thing. Gun Kata as presented in Equilibrium isn't something that is about being the most physically able person. But someone could can run through mathematical equations in the middle of combat to maximize kill radius or some other hooye like that. But its something that could be developed. Especially with the +2 to mental limit for mathematical stuff echo, and analytics.