GM's coolant issues is not so much with the coolant but the cooling system--contaimants getting in.
Ethoyle Glycol is the same no matter what same can be said for Propyle Glycol. I say use either but keep it changed regularly (every 18-24months) and use the softest water possible. Is distilled or deionized water need no but yes it is better--need to ask yourslef is it worth your money and time savings.
Ethylene Glycol doenst boil off which means that you can boil it forever and it will never freeze but propylene glycol will boil off meaning it will boil then be able to freeze
Green coolant eats through aluminum parts if it is not changed regularly. Green coolant builds up an electric charge(or something like that) and starts "eating" Aluminum with age. This is why GM cars have changed over to dex-cool. That fixes that problem. But like someone said, with dex-cool contaminants form in it after a while. I don't know if contaminents are "getting in" is correct. Age causes the dex-cool to gel up. The contaminents eventually build up and start causing cooling problems
I would never recommend switching over because these two coolants do not like to mix and will once again gel up when mixed. It is tough to get all of the coolant out and switch over anyways.
Solution is to flush your cooling system out regularly.
Stick to good ole prestone with a 50/50 mix and a jug o watter wetter, change it out every 2 years with a tstat change and you can't go wrong .
Lowering the amount of coolant mixed with water like a 25/75 mix your starting to look for trouble, especially with the SC's. The coolant increases the boiling point of water, and the less coolant you have in the mix, the sooner the water portion will boil up on you..... but you CAN"T mix the other way either like a 75/25 mix of coolant to water because you want a "safety" margin that when things start getting TOO hot, the WATER portion of the coolant mix will start boiling off to lower the pressure..... remember that gas compresses more than liquids.
dump all your coolant, pull your freeze plugs and cut the fan....soon..very soon you wont have to worry about it..And I guarantee you'll keep very low miles on your engine too...