I haven't looked into the DEX-COOL thing for a few years, but I'm not concerned. Pretty sure it's not an issue anymore, as long as you don't go crazy long on the change interval.
The Yukon has been running DEX-COOL since new, and I haven't felt the need to switch. Apparently, if you do switch, you need to do a very, very thorough rinse to get all the DEX-COOL out. If there's any DEX-COOL left, apparently that's even worse when you mix it with the other stuff.
Just checked, and I had a coolant change done on the Yukon after four years, and then again after another four. Five years would probably be the absolute max you'd want to go on that, IMO.