I've only read stuff with others talking about it, I really know little about coolant..
I do think a lot of the Dex Cool problems I've read about come from not changing out the fluid regularly, but air in the system can cause problems, as for whether or not it also increases acidity, that I do not know about..

The coolant in the overflow does not flow throughout the system and get heated up, the supposed main problem I read about air being in the system is supposed to be"Trapped air could allow for increased temperatures around the hot EGR passage in the plastic upper intake manifold, leading to failure of the manifold, internal coolant leaks, and severe engine damage."
That is why the bleeder screw is supposed to be there, so I guess the problem isn't a dex cool problem really...

If it is ok to post it I can post the link to where I found that info, which led me to drilling the 5/32" hole in my t-stat..

That is correct, any trapped air could cause a hotspot.

I believe we actually did a study here awhile ago pertaining to lower intake gasket failure and concluded that Dex had nothing to do with it. It was just the heating/cooling of the gaskets that lead to premature failure.

Some people here use the bleeder screw, some don't. I for one, do not use it. It takes to long for the engine to warm up to opening temp. I find it easier to remove the thermostat to "burp" the engine. Others will park the car so it sits at an angle.

Another thing some people do is use different thermostats during the year. I use a 195 during the winter and a 180 during the summer.