+1 what Ogre said. For truly cold water a neoprene is impossible to beat - they are the only option for long dives in water colder than 40 degree that will not leave you feeling the cold at some point in the dive. And a snug fitting un compressed neoprene suit swims very nice - almost like a wet suit.
On the other hand, they are too warm in water warmer than about 60 degrees, especially if you end up working hard in them, so they are not an option for Florida wreck and cave diving.
Trilaminate suits are nice in that the insulation is adjustable and you can wear in them in 80 dgree water with basically nothing underneath or wear them in 40 ish water with heavy undergarments.
However it is far from perfect and the temp adustment possibel with undergarments fo varying thickness has finite limits. Since the material in a trilam does not stetch the cut of the suit needs to be generous enough to allow a full range of mobility in the thickest undergarments you intend to wear. That either limits you to fairly thin undergarments and cool rather than cold water (55-60ish) or means that in thr 70 ish Florida cave environment you will have a suit that is baggier and draggier than is optimum.
One additional feature is that you can get a trilam with self entry zippers. That is both a blessing and sometimes a curse. The normal DUI diagonal across the torso zipper requires an extended torso that adds bagginess, drag and a fold to try to limit the bagginess. This aggravates the already generous cut needed to ensure a full range of mobility.
Whites and Andies dry suits use a different sef entry design with the zipper starting at the top of the left shoulder, running down the front of the chest under the inflator and up to the top of the right shoulder. It provides easy self entry with a shorter and trimmer torso like that used in a suit with a traditional across the back of the shoulders non self entry zipper.
So in effect the diagonal across the torso zipper is my least desired choice in zippers.
+1 on the Whites Fusion. In addition to the superior zipper arrangement, it offers a very liberally cut waterproof layer that goes under a stretchy exterior skin. The skin keeps things slightly compressed, helps control air movement in the suit and prevents any excess bagginess to reduce drag in the water. In effect, the suit swims very much like a wet suit and avoids may of the traditional dry suit control issues. In addition, the liberal cut of the water proof layer, allows for a great deal of variation in undergarments (or even seasonal weight gain/loss) without compromsing either the excellent mobility of the suit or the streamlining of the suit. I have owned several dry suits of various types over the years and none of them offerred more flexibility or range of motion than a Fusion.
Finally, the exterior skin takes all of the abuse in a wreck or cave and because it is free to move and stretch a bit, it is much more durable than you would expect it to be. In my experience it is more durable and leak resistant than a trilam.
