I prefer the pouch style as well. I got a Peanut Shell with Ellie. I've only had one ring sling (a bulky padded one before I knew any better

LOL!) and the rings slipped all the time and it never felt adjusted right. It had plastic rings...maybe the metal ones hold better? Not sure? I really want a solarveil sling (with a summer baby) this time, but not sure if I want to spend the extra $25-30 I've seen for a pouch one...so I may end up trying a solarveil ring sling.
For twins, I would think wrapping would seem less bulky (than two slings) since you could wrap them up really close to your body. I have no idea about putting two in one? I would think that would be hard in a pouch since they're pretty fitted anyway...but, then again, I've never tried it.

Do you know of any BTDT twin mamas you can ask? Of course, when they're a little older (good neck control) you could pretty easily do two mei tais - tie one on the front and one on the back. You know, I bet you could do two Kozy (bigger mei tai - more padding at the neck area) carriers with twins from early on. The lady who makes them wears her babes in them from newborn stage up on her website. I'm such a mei tai lover since even the best sling does bother my neck and shoulder after awhile. Mei tais distribute weight more evenly.