I have both the stereo version and the mono version. When listening to the stereo version I found that this is a crisper remaster and find myself hearing things I once did not hear before burried in the mix. The mono version is quite special in itself because these are the actual masters that they focused on and perfected. They sound completely different than the stereo versions IMO. I tend to listen to the mono version more.
If anything buy the mono version before they get completly sold out then save up for the stereo version.
-e