I'm in no way a nappy expert but am having to change things around to deal with a heavy wetter as well! I used totsbots/motherease/cotton Diddy Diapers with my eldest boy & we got on fairly well with them but have had to rethink things completely with my 2nd boy. He is a very very heavy wetter and is also quite chunky around belly and thighs at not quite 6 months old. I've had to completely change my nappy stash as anything like tots bots gets soaked through within 30 mins.
I needed something fast-drying so am using mainly Bumgenius V3s during the day. Although the microfibre inserts are not great for heavy wetters, the nappy lining always feels dry against the skin and I also use homemade fleece liners. I've boosted the BGs with little lamb bamboo inserts plus an easy peasy hemp booster topped with the BG newborn microfibre insert and this is working well although I may look for a different bamboo insert as the LL ones are not quite as absorbent as I'd hoped. DS's bum hasn't been wet at all and he hasn't had any leaky nappies - so the BGs have been a big success.
I also have some Real Easy nappies (old style) size medium and I've been using them as a night nappy, they are working really really well for us. They have a sewn in hemp insert plus a microfibre pad and a stay-dry inner fleecy lining and they are very adjustable and good for chunky thighs. They have a massive pocket for stuffing with extra boosters, I add a folded P'tit Dessous insert for overnight and in the morning this is wet but not sopping, the hemp is also damp, the baby however is dry without any red marks on thighs etc! The old style Real Easys are being sold off cheaper at the moment.
I also have a few Micro Diddy Diapers which I boost with the LL bamboo topped with a fleece liner, medium Thirsties wrap on top, these are ok during the day if I run out of BGs and am staying around the house but they do get soaked pretty quickly.
The other nappy I've used at night is a Nature Babies Lovable (microfibre pocket nappy with fleece inner), the pocket is huge so can be stuffed with loads of boosters, I always put a hemp one in plus one or two LL bamboo and it has its own microfibre insert on top as well, nippa fastening, extra fleece liner, Thirsties wrap on top again, it is quite a good nappy for nights as the fleece stays dry against the skin but not as reliable as the Real Easy for us, as the microfibre can get quite wet.
I have a Wee Notions night nappy on the way which I am really looking forward to using, and after taking advice on here I'm planning to use a fleece soaker over it rather than a PUL wrap, I have also bought a fitted hemp/cotton nappy to try although it may be too slow-drying to use often.
I love the classifieds, it has been really easy to find nappies, inserts etc to try without having to spend loads on brand new stuff. There is a "Wanted" section as well which you could maybe post on if you have a particular nappy in mind?