I'd say to leave them on. Maybe not being noticed for 1 extra turn could save you just as often as the other skills?
Gods:
Oka is usually a good god choice as he might provide cool stuff.
I haven't explored some of the new god options.
For sneaking, I'd consider a magic-based god that can help with going invisible or fast, or can provide some firepower to finish things off.
Alternatively, since I like slightly off-beat takes on roles, one that gives you a nice escape/summoning option could be good (eg Mak or Trog). This would be used when that baddie you're trying to stab in his sleep wakes up and alerts all 5 of his friends who were just out of your LOS on the previous turn...
For example, I recently had a good stealthy-stabby hill orc priest. Despite the poor aptitudes he got to XL27, and could take out dragons in a single stab, because he could just recall followers and surround them with warlords when subtlety failed.
Also, in trunk, I've had some luck going with where my early finds take me: If you see an altar then consider that god; an amulet of guardian spirit can be a lot of extra HP for non-casters; I'd like to try Lugonu if I ever get an early teleport control; and so on.
edit: I didn't see galehar's comment about the change in trunk until after I wrote that - you might not want to worship Trog as a caster.