Opinions are like exhaust pipes...everybody has at least one.
To me the deciding factor against Dex-Cool was the fact that it doesnt lubricate water pump bearings as well as green stuff, plus it has a long history of not playing well with plastic parts (like we aint got enough of those)

There are those who swear by it since it is organic in nature and it does last a very long time...BUT as its water base evaporates away it will leave a brown sludge like residue behind. This is compounded by added regular tap water to the cooling system. Dex works much better with distilled, deionized water, but how many of us keep that around for just such occasions.

For me personally Dex-Cool has more cons than pros...and thats my exhaust pipe and I'm stickin to it. (no matter how many times I've changed tips)