There is nothing wrong with Dexcool in an engine that was designed for it.
The duramax was....surprise....designed for dexcool! There are no materials Anyone who thinks/has-heard-from-someone that its "bad" or "causes problems" is incorrect. All of the seals in duramax's were designed for use with Dexcool, and green antifreeze can actually degrade the life of some of the rubber seals/gaskets. The only duramax's that Ive seen dexcool actually cause problems in, were from people mixing green antifreeze with the dexcool.
The old Gen II small blocks and 4.3's werent really designed for it, thus all the horror stories from the mid-90's about Dex-cool. And back then, everyone was mixing green and Dex-cool, which added to the undeserved bad-repuation that Dex-cool still hasnt quite lived down.
And Dex-cool has gone through several different reformulations since then. The current stuff is
fine. Id love to see actual studies (not someones 'intuition' or 'gut' or what they've heard from some idiot mechanic down the street at Billybobs local garage) that show the
current dexcool has problems in modern GM engines that were designed for it.
If you are still stubborn and want to run green, then go ahead, and have fun changing the coolant once a year or every X thousand miles...especially on the 06+ trucks that dont have a drain plug.
Which brings me to my next point about the 06+ trucks that dont have a drain plug. Yeah its annoying...and GM probably saved some money, but think about it....Dexcool is super long-lasting, so you'll likely only have to deal with that annoyance once or twice in your trucks lifetime.
And as far as the other "fancy" coolants (the caterpillar stuff, etc), its going to be a bigger PITA to find some if you are far from home...every auto parts store has dexcool. Advance Auto even has their generic brand dexcool thats only like $1.50 more than regular stuff....
JMO.