We have tried lots of different nappies at night and can recomend the UDNN in soy and WNNN. I prefer UDNN I think because they dry quickly and are so soft (we have very hard water) but WNNN come very close and I actually have more WNNN as more have come up preloved. WNNN are more funky and pretty.
I wouldn't use baby behinds for nights after about 6 months. THey make great day nappies and I use them at night for my 8 week old if she has no dry WNNN but there is no way they would last on my 18 month old.
OR if you wanted some cheap night nappies to try, I have some hemp and terry stuffies I was thinking about selling? They come with hemp inserts but you would probably need to add boosting, but there is a large pocket for this. These (with boosting) last the night on our 18 month old, but I don't like nippa fastening nappies more than anything else, and she has enough nappies now not to need them. Would be looking for £4 each posted. They still need a wrap. Hopefully I am allowed to post this here - I am not trying to be cheeky, I just wanted to help