I hear this alot, but I still don't know why people say this.....While most of my diving has been florida and carribean diving, when I dove in the kelp at Catalina, or under the ice in Lake Erie, I did not feel any difference, other than that there was no drift current.
If what everyone is talking about is the differences of switching your exposure suit from cold to warm, or vice versa....I don't get this either. One or 2 dives to get bouyancy issues optimized in new suit....and the dry suits suck, as to the lack of glide through the water, but not so bad that it changes comfort level in the water--and we have to use them in winter or tech dives in Fl anyway.
I will concede the NorthEast divers that go out in 6 to 9 foot seas, and feel like it is glassy flat out, are definitely a "hardier sort" when it comes to comfort on boat rides in rough seas