Thank you all for your help and reco with this.
Here's where I am on this:
On one hand I like the idea of a lightweight, loose-feeling and breathing drysuit like the Kokata but I'm a bit paranoid with the idea that the suit could fail and water gushing-in would mean drowning or rapid hypothermia. I just don't know how much this kind of suit can be trusted.
On the other hand, wetsuit is a pain to put on and off, somewhat movement-constraining, but a little water sipping through the zipper or the collar during sailing is not the end of the world: it still offers insulation and is inherently buoyant.
I am sometimes the only one sailing where I am on Lake Michigan and can only rely on myself if some unfortunate situations arise (I.e. Injury, rig or components failure, etc.).
Also, my experience with O'Neil wetsuits is that their neoprene is super flexible, very resilient but lacks ankle straps because they are primarily designed for surfers. I sail with footstraps on the rails and water inevitably gushes in and can even expose skin by rolling up the leg-end ...not good. NPs are better that way but I never tried one that fitted right on me!
The Ion Fuse seems a bit overkill for the conditions I'm willing to go out (48-50 degree air and water temp).
The Ianovated wetsuit is interesting with the upper body that seems a bit looser fit but I can do without the hand warming thing.
Then the Dimension Dry/Wetsuit from Promotion is also nice and loose on top but the shoulder back zipper is super hard to close/open on your own (first-hand experience helping someone last year...)
Man, I've been agonizing over a warmer suit this entire winter.... gotta make a choice...