Hiya. We switched to cloth just over 2 months ago and have never used a proper night time nappy on either baby. In fact at the moment we always use ebay cheapies at night. DS is 19 months & we put a charcoal bamboo booster in with 2 normal bamboo and he will sleep 6pm-7am and wake up dry. DD is 5 months and she has a MF insert with 1 bamboo folded in half (and pushed to the front as she is a tummy sleeper) she will sleep 14 hours and wake up dry.
Maybe my babies aren't heavy wetters at night but thats been fine for us so far.
*just remembered, we use minkee rather than cotton as we found cotton wick a bit x