I personally think sneak should be disabled in combat completely, although I've been abusing it in my own solo runs.
First reason, is the combination of sneak and rain/contamination, the player gets to sneak while the enemies treat the player as if he is invisible and unable to locate the player, and die in poison zone eventually, I was able to beat the Dallis encounter at level 3 using this method and I didn't like the fact that I could do it.
Second reason, is that you can freely stall for cooldowns in sneak, you can kill an enemy on high ground, out of enemies' sight range, sneak, wait for all cds to be back up, go in again. I think, having only chameleon cloak as invis and stall method is a sweet spot, anything more is simply overkill.
As for guerrilla, can really just treat it like rest of the 10 bad talents that were never properly balanced, and assassinate as a combat opener, or make it so assassinate deals bonus damage when out of sight range of enemies, regardless of whether sneaking or not, and tune the bonus damage numbers as well the cd of the skill.
