How important are small improvements in sound to you Mgattmch?
Some people feel that music played off a server is noticeably better than the same music played from a cd, even when they ripped the file on the server from their own cd.
Also, HD Tracks may have gotten a copy of the file that was used to produce the cd, which may sound different (maybe better?) than the cd. I imagine that the production of cds can be done badly, resulting in the cd not sounding as good as the file it was made from.
I don't know if you will be able to find out where the download on HD Tracks came from. From posts I've read, they don't seem to reply to these kinds of questions.
So my advice at this point would be to wait for a higher res version to become available before you purchase a new version and to rip your cd to your server and see if that sounds better to you.