Can't really opine on the technomancers, I don't spend much time with them.
Everyone needs a R:6 Personal Assistant on their commlinks. Even deckers need them. Spend a cyberdeck program slot on an emulator and put a R:6 one in there. They're stupid OP and need a nerf IMO. At a bare minimum, PA rating should be limited by commlink device rating. The author of this section even agrees with that limitation.
Agents are also a must have. Get those extra dice!
Custom cyberdecks are not a must have. They're only going to appeal to a certain playstyle because they have a rather punishing wild die mechanic that you can't opt out of.
The gameplay rules section has a few must-have actions that your matrix specialist will get use out of. Threat Analysis is the most powerful of those, and it too needs a nerf. I'd suggest limiting extra dice to 1 per two hits instead of 1 per hit.