I haven't used it on my babe yet, but I have a XS elbee I bought for the next baby, and it is about the same size roughly as all the other big-running NB dipes i've bought. And elbees fit larger than they look IMHO. I asked some elbee using mamas and they said big babies fit into XSs with room...(my first was 9lbs 5oz, so I need BIG diapers...lol) for quite some time.
Mine is OV, which seems the stretchiest....my mediums fit my DS with the tightest non-crossover snaps, and he's wearing some larges right now
It's super cute though, just makes my uterus go pitter-patter...hehe.