I am just repeating what I have heard, and seen.
A good friend of mine is a tech at the local G.M. dealership. They are having problems with Dexcool cars. In fact, my Mother in law has a 97 Fireturd with about 70K miles. Her car started running kind of warm, and my friend happened to be over the house that day when she was visiting. Long story short, we popped open her system and it was crusted full of scale and corrosion. He said they hare having a problem with this and have been having to replace radiators, etc. etc. on fairly new cars that are gunked up. My mother in law took the Bird to the local dealer. They had to pressure flush it several times to get the lumps of crud to start coming out and replaced it with the regular old green looking stuff when they were done.
So, I guess this is going to be like a lot of other things out there, everybody will have some sort of opinion or different experience. I swear though, here cooling system was a nightmare, and I just can't imagine that should get so bad that soon.