I am just going through the upgrade process. Logic has been on a downward spiral for years now in regards to compatibility with digidesign. So far, 3 days into it, this combo seems as though it might be the one that brings us TDM/Logic users to the rock solid days of OS 8.6. I can even open a song seconds after closing the last song. The CPU has not crashed yet…amazing! You MUST use Pro Tools 7.1cs4 Depending on your third party plugs and instruments, there are many things to upgrade when moving from PT6.x to PT7. Sound Toys are at 50% right now. I spoke with tech support on Friday and they are working on full Logic 7.2/PT7 support. As of now, all the new plug ins don't work in Logic (they do in Pro Tools) this includes… Tremolator Phase Mistress Echo Boy Filter Freak Crystallizer The older ones seem to work fine… Speed Sound Blender Pure Pitch Waves Diamond seems good though I have had some weird stuff…Rverb compact works but would not load my old song settings. Installing PT7 required me to turn off firevault on OS 10.4.5 that in turn resets the machines ID. So some things authorizing your drive need some new codes. Ie.Ivory Native Instruments no longer works as a TDM plug anymore until someone makes a RTAS wrapper. Guitar Rig live input from DAE goes away. Here is my system- Dual 2.5 G5 4 gigs RAM 2 192's Pro Tools 7 slot chassis (SBS from 2000) HD 7 (core, 3 Accel, 3 process) PT 7.1cs4 Logic 7.2 Filter Bank Sansamp Waves Diamond Sound Toys TDM Effects (all) Amp Farm Echo Farm Oh…many more of the Digi plugs… Hope this helps