I currently dive with a XCel 6/7/8 semi-dry and an aeroskin skinsuit. The skinsuit was supposed to make it easier to get in/out of my semi-dry, but it also seems to help with making the water temperature seem just a bit more comfortable/tolerable.
For freediving, I like this setup in 50F water. I would say the water feels like 70~80F in my suit and that's just about where I like my water temps. There some occasions where I've noticed suit hugging from the constant diving/surfacing but that's easy to fix by pulling the lower face opening of the hood to relieve the vacuum while on the surface.
On SCUBA, I have noticed it a bit cold at depth of maybe ~60ft (49F) because of the thinning suit and longer submerged interval. I would guess the suit would start to feel like 60~65F. For me, that's cold but tolerable.
If I had to dive where a hood is required, I prefer the semi-dry as a personal choice. But if it's any more colder, I would start looking into a drysuit.