While the edge trem is said to have a little more mass than the lo pro edge, i haven't noticed any sound difference between those 2.
A tremsetter (the thingy that he has installed in his trem cavities) basically rescues you when you're breaking a string, but kills most of your flutter.
Vai uses the lo pro edge, satch uses the edge, some of my guitars have the edge, some the lo-pro, and I don't care. Although I think I'm more of an edge guy. But the point is that this discussion is pointless.
Get what YOU like the most. You'll be able to do insane whammy stuff with all of them. The "edge vs lo pro edge" discussion has been heavily discussed already, please do a forum search.