I own both a White's Tropical and an Oceans Systems SARR (with attached boots). The White's does not breathe - it's a simple, impermeable shell. The ankle seals are a PITA on a moving boat, plus it's a back zip suit so one always has to trust someone to zip it correctly.
The OS suit is a rapid self-donner, since it's designed for rescues under arduous conditions. I can get in that thing and be zipped, locked and loaded in maybe a minute. I can't get into a skin suit or thin wetsuit that quickly.
The White's is a thinner laminate material - pretty tough, but Steve Gamble at Gamble Scuba told me that I have only a few years left before the seams start to delaminate. That will be the end of that suit.
In terms of comfort, in warm water, a nice thin wetsuit is more comfortable and of course requires no adjustments. With any drysuit, you're always going to have to mess with the buoyancy during the dive. Just a fact, Jack.
If you're doing a lot of recreational dives like on a liveaboard, a drysuit will be worth its weight in gold around the 5th dive of the day when you're getting a little chilled and the wetsuit was already clammy two dives ago. Dry is nice for that.
The 30/30 is a great suit - I almost got a used one, and I might have gotten one at DEMA this year except that DUI is not attending. Oh well. That's a LOTTA coin for one though. For $200, I got two used White's Tropicals plus a too-heavy new Pinnacle undergarment. I gave one of the suits to a friend, put about $200 in new seals all around (takes 5), and stored the Pinnacle for diving colder.
I'll dive wet now for a while, until the late fall, and then back into the dry suit (most likely the OS) wearing my shorts and t-shirt under it. Winter and nights, I like warm so I'll wear the OS nylon poopie suit under it.
And always, always the p-valve.
Other questions, fire away.