I just buy the "regular" caps since they're like 1/2 the price at my LHBS vs the O2 absorbing caps. I'm having a hard time seeing how they could be an advantage if you're bottle conditioning. Wouldn't the yeast eat whatever O2 you might introduce during bottling? I guess if you're bottling from a keg the caps might make a small difference. In any case, after they're capped, the bottles aren't 100% sealed. They can still allow air to get in, albeit very very very slowly.