I am in the dilemma of upgrading from Pro tools 7.4HD to 10HD. We currently have 2 rooms running 7.4 with HD2 accel on windows xp machines with the legacy 192's and sync I/O's. I would like to upgrade to 10HD with our existing hardware running on osx Lion systems. Besides the $, what is the difference between a clean 10HD install and a 7HD to 10HD upgrade? I can't seem to find the software alone without a trade in/upgrade including new hardware/cards etc.. except on ebay. I don't see any advantage to upgrading since I am installing on new computers anyway. Any suggestions?