I have absolutly no experience in sneak its been 2 days i play a sneaker to try new things and i must say its the more fun character to play.
I agree with the fact that most of the kills you do with a seaker are very retarded. Kirkor is right to mention it, wih a sneak you grab a crap leather armor a p90 and you can basically wreck havoc anywhere. Damage of the p90 with 3 brd is absolutly insane.
P90 is okay since it really does damage if you get close but you shouldnt be able to be a walking turret with bozar or avenger.
And as Wind_Drift already said, the weapon penalty should be for whole inventory, not only for hand slots.
It will prevent bozar sneaker or lsw or avenger yes, but what if you kill a guy with an avenger loot it, your sneak skill got a penalty someone else pop up and see you from 30hex and kill you
Skill cap at 250 + stealth boy to get 300 is a good idea if stealth boyz can be farmed (for example like in ares but in bigger quantities?)