Hello. I just upgraded 6- Gold native, 1 Plat/Native & 1 Plat TDM all v 3.5 to V4 Straight forward and no problems. I used apples remote desktop to upgrade all computers from one workstation. (Slower than screen redraws than operating the machine directly , but faster and certainly convenient, doing all from my house and not going downtown to administrate all those machines. Also the same waves codes worked in both OS9.2.2 and OS 10.2.4 (same drive separate discrete partitions on 2 of the Macs and integrated systems (( same drive/partitions)) on the others) My issues are with OSX midi and not plugins. Apple needs to look back at OMS and dedicate a team to at least bring there Core Midi up to the old OMS's capabilities. Core MIDI is such a downgrade. There's my 2 cents with change to boot.