Yup, the mothernature nappies have to be worn with a waterproof over. I use the pep ones beause they were so chaep, but to be honest the MN waterproof is best (I have 1 of these) because it fits snuggest.
I've been using my MN nappies since James was born and am VERY happy with them, aside from the fact that they do tend to take a little longer to dry, they are soooo easy to use. I also use the normal square ones at night because they are bulky for during the day, but it meant that I have more nappies and now only need to wash every third day. The glodina ones do fray a bit, but are much thicker towelling and are really absorbant for night time wear, especially with a fleece cover rather than a traditionaly PUL cover because it allows some water to evaporate (It means in the morning clothes are slightly damp, but it keeps too much moisture from sitting against his skin. I also put extra barrier cream on his bum at night (I us the woolies pure earth baby range, which I think is Fantstic - I refuse to use vasaline because it is petroleum based and we use enough oil in our cars:) - First think in the morning and after bath I use baby powder (also woolies range) on James bum as well. It absorbs any extra moisture and provides extra barrier to help the bum cream. So far the only 2 times he has gotten a rash were when I used the johnsons babywipes that I was given for a free sample and when I put him in a pampers diposable. Now when I go out I use the cherubs ecowipes which are biodegradable and flushable and have bought the seventh generation chlorine free disposables to keep in my bag for when I need an extra nappy (unortunately the MN are bulky, so I usually only keep 1 spare in my nappy bag). They are expensive disposables, but given that I only used half a pack of the size 1 before he outgrew them I am not too fussed!
Bamboo is a great product. It is fast growing, utilises more CO2 than most other plants (thus letting off more oxygen), very ecofriendly!
As for the Carlton Ultra. It is slightly more "rough" than the MN liners, but hasnt bothered my little boys skin at all yet. I wash them by hand, but you can put them in the machine with your nappies in a mesh bag!