I really think there's not much difference between these and the 6's...not enough to matter anyway. I have both sizes of cruisers, and it might be like a half inch to an inch longer. They aren't "tall enough" for me - if they were, I'd have no problem with the waist - but the sides have to go around my thighs instead because they're short - since, ugh-dugh - they're for babies. I wouldn't expect them to fit. Heck, for height I even have issues with a lot of adult small size diapers, which would all fit my waist....this just accentuates that problem.
I used to be able to fit in to size 6 baby dry's, and i had a 32 waist but it took some major stretching, they also only held about one good wetting and any more would cause it to leak once you sat down. Though now that i have lost some weight and only have a 30 waist maybe i can. They are a good stealth diaper but i think that anyone would probably be better of with underjams or goodnights for that.
There a good diaper, though the main problem ive seen is from what ive also heard from those who review the underjams, sides tear. I cant sleep with them due to this fact, though they do absorb fairly well so to me I consider them good.