Others have struggled and abandoned the coccoon setup coz of 'cold spots' above but mainly below,
There's a big YMMV with this though, and my suspicion is it's down to the hammock you use. We have two cocoons, one we use with a dd camping hammock, and the other (mine) with a parachute-silk style double hammock (e.g. the nomads land one at Lakeland Bushcraft, which is the same). Cold spots have been reported with the dd one, but not with mine. Infact, I've never slept hotter. I suspect that's down to the size difference - the nomads land hammock is much bigger, wider in particular, and that presumably prevents any void being formed below. It's also single skin (and lighter) so maybe your body can heat up any air pockets below easier.
The mozzie thing is one of them, much like most bivvies, it's not going to keep them out without a mozzie net. Having said that, I never use my net, I can live with a couple of bites in the morning. And on the plus side, It's a very light setup that flies up:
IIRC
Hammock: 450g
Cocoon: 1300g (this is really from memory though)
Tarp: 750g
Slap straps: 250g
Cordage/Krabs/ti stakes: 250g
3Kg on the nose. Going with the travel hammock and quilt setup will add a kilo and a half to that.
Just out of interest, my bivi setup (similar, in the sense that there's no real gucci kit, but not cheapest of cheap either):
Rab Storm Bivi: 500g
MSR E-Wing: 200g
Stakes/guys: 100g
Alpkit Skyehigh 600 bag: 1250g
Slim Airic: 750g
2.8kg - surprising, so pretty close. Probably close in cost as well.