The "short rail" models don't really look all that different than the later ones. CZ apparently went to the longer-railed version after some issues with frames cracking. (They probably changed and improved the metallurgy, too, as time passed.)
CZ-75s (both the pre-Bs and Bs) have been in a slow but constant state of change. They've introduced a number of changes, and brought out a lot of different variants.
I've had a SIG P-210-6; it was a nice gun, and superbly accurate, but there were things about it I didn't like. (Low capacity, sharp edges, hard-to-use mag release, difficult to release safety, so-so sights.) I now have a SIG P226 X-Five that isn't pleasing me all that much.
My next big purchase will probably be one of the top-end CZs for IPSC, like the Tactical Sport, but I may have to sell the X-Five first.