We had a M and L Lambkins wool cover with Aplix. We used these covers exclusively at night b/c I found them quite bulky. But they were *wonderful* for night - never had a leak. My dh calls them "giganto dipe" b/c of the bulkiness, but others have said they don't find them bulky at all. I like the gussets and the Aplix adjustability.
I thought this cover ran small and was cut in a way that it doesn't fit well over any diaper I owned. It didn't even fit over a snappied prefold for us. I think it would work fine with a trifold prefold, but then we'd have poop in the cover, which is not fun with wool.
We have used the front snapping covers in a medium and large, the hemp prefolds, and the fitted diapers. I love them all - the diaper has held up well and fits nicely on my average-thin and tall daughter. We primarily use wool at night, and these NEVER leaked for us. The prefolds are also very absorbant, and occassionally would take an extra drying cycle - but completely worth it to me since it was so absorbant (and they didn't take longer than my other diapers.) The size was also better for us in terms of length/rise. I didn't have to fold anything over - it fit perfectly in my covers from Susan. I am excited to try one of her side-snapping covers with the merino binding, they look and sound great!