I own a Kokatat and a Sweet top. I can not discern a difference in dryness or durability.
If you are really that worried about the "burly-ness" of your gear, don't buy paddling drywear at all. Buy military spec.
Kokatat makes a military spec drysuit that is similar to the GFER, but the base fabric is not nylon based, it is NOMEX III, which, in addition to being chemically similar to kevlar is also flash fireproof and fire retardant. Its not bullet/knife proof, but is a LOT tougher than the standard nylon that kokatat and Sweet use.
I own 4 of these suits and they are badass. A bit heavier, but tough as nails. Downside...no skirt tunnel. Which is a non issue for rafter/Duckyists/Suppers.
Actually, I see that a local Mil Surplus shop in Vancouver is selling one that I traded to them for some Huge watertight cases.
Here is my original post about these suits with pics.
Kokatat M.A.S. Info?
One for sale
Kokatat GORE-TEX Drysuit