[tobeychris]

The last letter is the latest revision, and should therefore be most stable.
ie: 20924 v2d is the most stable 20924 SYS released.
20755 v2b is the most stable 20755 SYS released.

As for OEMs... there isn't much in terms of stability... normally newer apps are better, but once in a while there turns out to be a bug in them, but OEM folders are easily swappable, so you can just take the older one in most cases, drop it in, and it will work.