I can solo missions rather easy. I normally load Ballista or Howitzer, both with a mix of Despoiler. Lately I have been loading several DoTs and seeing how many I can put on ppl. It's funny to watch someone die from a DoT after I die, especially when they try to HJ away. Logic Cannon 2 and Code Nuke 3 can do really nice damage after Insidious Code and Overclock is used. I haven't really messed around with Ravager or Network Attacker trees though. I have used portions of those trees to help MA/GM while they are in IL which worked really well.
MrMatador
Hacker if used right is a powerful tree still, it has some of the best abilites to counter and aide other trees too.
Ballista is a great damage dealing tree, and things like howitzer are great for group attacks or farming large number of npc's that are gathered.
Look at the passive buffs trees give also to get a good loadout setup.
As for solo, a hacker can take on any tree, you will find though IL loadouts seem to be ones to watch out for.
Howitzer can solo a box 4. Not nerfed, just have to use it right.