All anti-freeze is definately not the same. They differ in their silicate levels, and the inclusion or exclusion of phospates, for one thing.
I did read a lot (but not all, its too much) of the debate on the threads you posted (thank you!), but this debate seems like more of a theoretical thing than a practical debate (i.e. a tempest in a teapot!).
Changing the anti-freeze is far from a daily thing. How much is genuine MB anti-freeze? $10 per gallon? $12? Compared to $7 for Prestone? You only need 2 gallons. So, we are talking about saving $6 to $10 every few years on anti-freeze??
One thing the debate here (and on many, many other car forums) tells us is that there *is debate* on the issue. I'd rather spend the extra $6 per few years, avoid the debate altogether, and be *100% assured* I am putting the right anti-freeze in my $37K car. To me, its not even worth thinking about to save $3-$5 or so per year.