A Great Lakes diver, I've been diving with the blue ZipGloves ever since I bought a drysuit. While dexterity was an issue the first few dives, a little practice quickly took care of that. As a DM and later an instructor, I've switched out regulator hoses, replaced o-rings and fixed many other gear problems that arose after I had suited up. Because of this, dexterity has not been an issue underwater either. Tasks like writing (legible!) notes, rigging and blowing a lift bag, or helping student divers with wet gloves (and cold hands!) tuck their mask skirts back under their hoods are pretty easy to do.
I hate glove liners that smell like moldy shower curtains, and the ZipGloves are so easy to take off and put on that I remove them after each dive day to dry in front of a small fan. If you tuck the glove in on itself around the seal, it's easy to pinch the seal closed from outside the sleeve. The soapy water suggested above is a great help...however, a spritz of SeaVision defog or even a good lick around the seal will do if you forget to bring the soapy water with you.
For me, dry gloves are good; warm hands are good; and ZipGloves are good...but every diver is different, and DUI Demo Days are a great way to find out if ZipGloves are right for you.
Whatever you decide, I wish you warm hands and good diving!