What does Guerilla mean? Guerilla is warfare, where you launch small surprise attacks on you enemies, so he can hardly prepare and you get the advantage. So for me the purpose of Guerilla was always only something, which boost your first strike on the enemie and not something that buff infamous exploits like: sneak - attack - sneak - attack - seak
Just standing behind the enemie and being able to 'disappear' is just ridiculous unlogical as a concept.
In D:OS1 as a aero-rogue you had two stealth skills, that was all I needed. I never needed sneak and in late game I even hardly ever needed stealth either. But now I think there is only one stealth skill left and also combining stuff like aero and rogue gets kind of killed by the armor-system anyway.
