I've taken the plunge, and put the latest and (possibly) greatest version of the firmware on my T-Mobile MDA Pro.
The AKU3.2 is not an official firmware release, more of a homebrew (AKU3.2 is not available from anyone but Microsoft at the moment).
However it seems stable and without a doubt quicker than the AKU2.2 release I had before.
To do the upgrade you need the following download, and then have a read through the readme.txt included.
I've also included the Radio 1.13 rom, and the startup splash screen changer in the RAR file.
If you have any issues, then leave a comment, or pop along to XDA-Developers.
Also if you have a MDA Vario2 (or HTC Wizard) then pop along to Dan's site, he's done the same on his one of them.