Sneak is free invisibility. Small guns skill doesn't kill anyone without gun, the better gun, the more you get out of the skill. This should apply in sneak too.
The idea is that we got differend suits of armor that allow varying levels of maximum sneak in addition to the currently existing penalties (PA, CA and metal)
Example like this:
bluesuit: sneak 0. You can't sneak in bluesuit, same thing as you can't shoot without a gun.
Leather jacket
max sneak 180.
CLJ
Max sneak 250
Leather armor
Max sneak 200
Leathermkii
Max sneak 270
Now here's another thing: stealth boy is no longer a tool, but a crafting part. You combine it with any existing armor to create a sneak suit. This sneak suit now becomes a suit that allows you to sneak with full potential, which is 300. In addition it would give the +60 to sneak, but it might be capsized by the armor's natural sneak mods. It starts to deteriorate when you're sneaking, it can be repaired with sec or MFC.
What this would do is that sneak itself doesn't need to be nerfed. True 300% sneaking would become quite rare but effective and most sneakers would wear leathermkii which still gives decent max sneak. Trollsneaking would become pointless because easily farmed armors wouldn't provide good sneak and bluesneaking is totally out of question.