I dive two piece Sharkskin T2 in water down to 25ºC (based on logs) because I also want full coverage (so, also have a hood) and I'm a big fan. Highlights:
- neutrally buoyant
- can be used as undergarment if diving dry (I haven't tried it yet, I'd use it for warmer waters than what I have around here probably; I think maybe in the 20ºs?)
- less to worry about with folding/packing and how that affects performance (I usually compress it in packing cubes)
- I find it's less of an overheating problem on the surface, especially easy opening up the front zip on the top
- I also bring a Sharkskin hooded vest (not T2 but older Chillproof) for low-movement dives, like a blackwater or Manta dive in Hawai'i, to supplement warmth… only got chilly once after an hour night dive at the end of a week of diving
Mid/lowlights:
- some people find the fit "tight"; it's stretchy, and I think more comfortable than wetsuits above water, but this is a complaint I hear often enough. I'm using my regular sizing, which worked better for the two pieces.
- drying speed is… fine