They shouldn't have stat penalties. No one uses them except on snipers because they're literally worse than their non-adept counterparts. While we're talking about adept mods being outclassed by normal ones, quick access sling is generally just better than adept handling on shotguns, it'd be nice if we got an adept version of QAS that maybe gave 5 handling as well. Also adept icarus should just give more AE than the normal version instead of 5 handling.