I wouldn't recommend them for nights for a heavy wetter Nic - with the extra booster you can buy Isabelle lasts 3hrs during the day... Usually... Plus even the large itti bitti AI2 comes up smallish on Isabelle... There's no way I'd risk it at night!!!
You'd be better off getting a standard Minki instead as they're HUGE! (and probably cheaper too)... Our night nappies at the moment apart from night notions are: Puddlepants weedies (HUGE), Jimmy Riddles (again generously sized but I do add a booster) and a standard minki which is fab, it's HUGE!