Here's the deal, I own a DUI TLS 350 Trilam Dry Suit, and its great, always Dry, great Latex Zip Seals (which you can change if you split on site, I alway carry a spare set.) you can dive with light undergarments in semi Tropical temps or full blown hi loft undergarments if you plan a trip to Antartica!! Its the Rolls Royce of Dry Suits, check out any photo expedition and you will find every Diver wearing DUI. Go to a DOG Day and Try one out for $25. BUT....be ready to shell out $2500, if you want one. On the down side if you are a new Diver Buoyancy Control can be a Challenge at first, and all the Tri Lam suits are not the most Comfortable. I have also dived rented Bare Nex Gen, to be fair it was a Rental Basic Dry Suit, it leaked in wrist seals due to them being damaged and they need sending away to be repaired. Nothing Special.
I also own a Scubapro Everdry 4 and love it, its Soft, Comfortable, Low Drag, Easy Buoyancy Control for new Diver to Dry Suits. I wear for Dive Training in Quarry in NE USA, Water temps down to mid 40's with Mid Layer undergarments, mid 50's with Base Layer undergarments, and its less than 1000. However you need to be real carefull with the rollunder Neoprene neck seal if you want to Stay Dry......I regularly get a little wet in it through neck seal, but its not a big deal because the suit is Neoprene so you still do not get cold not like you would in a Tri Lam. I am taking it to Galapogas next month were temps can vary form 59 - 75, so it will be perfect. My advice, for now, get the Scubapro Everdry 4, its the a cheap flexible easy transition from wet suit to Dry Suit and sve your pennis fro either a DUI or the new Bare SB. Forget the the Next Gen. Just order slightly larger on the Scubapro as size runs small and it will give you more flexibility to add thicker undergraments. As to undergraments I love the new Bare SB Base Layer, its perefect under my Scubapro or my DUI.