My own nipples are small, and when 'just hanging out' lay naturally flat to the skin -- and either way, they work quite well (not that they don't perk up when I grab 'em to get 'em in there...but, no problems. And the Mr.'s are even smaller: they work on him too.)
I agree with kendra above: if you're superconcerned, the mandible type will grab on anything, too, so you'd have more control over _where_ and _what_ you were grabbing on to -- always nice to have more options AROUND the whole nipple area, but as these close all the way completely, as long as you could grab any skin anywhere, I can say they'd grab on to anything you'd probably like them to -- nipples or otherwise.
(p.s. -- imo, there are no 'stupid' questions. just fun-exploring-'what's next?! or 'what might I like or not' or 'what might work for me' questions!)