Man, I just realized we're going to be able to have a KHD in a fireteam with a tinbot... pretty much unbeatable in Infowar.
Although not a KHD, a Zhanying in a Wu Ming (w/ Tinbot B) link would be a close second, no? WIP 16 with -6 to incoming attacks is pretty crazy, even when your most dangerous programs are Gotcha! and Brain Blast.
I have idea about Kerr-Nau. Bit has as a upgrade hacking program Expel. So what if Kerr-Nau will have additional hacking program as Upgrade. It would be way to make him more interesting without need to add additonal skills to make him more expensive.
Frankly, for me the 25 pts of being a KHD with Plasma Rifle are already close to the "hard to fit" part... However, considering how he will be inside a fireteam (as a nexus), access to a defensive program like breakwater would be nice... and it would see some use!
You'd be basically always better off using Maestro, though. Since it's about the same spread but actually hurts your target back.
IMHO only Upgrades that would make sence for him are programs that can target other hackable units (HIs, Tags). Also I don't expect to see Nanoscreen, because only spitfire loadout has it.