This was my experience with my 6-core 3.33 GHz Westmere Mac Pro + 24 GB RAM + Lion 10.7.2 + Magma PE6R4-I + PT HD6 Accel PCI (HD Core card PCI is "revision K"):
- starting with the 64-bit kernel: PT HD 9.0.6 and PT HD 10.0.0 hang on 'Initialising hardware (DSI)', need to do Force Quit of Pro Tools HD
- starting with the 32-bit kernel: PT HD 9.0.6 and PT HD 10.0.0 work fine
I had the chance to do some tests with a HD Core card PCI "revision D" and the results are clear: starting with the 64-bit kernel, PT HD 9.0.6 and PT HD 10.0.0 also work fine.
After contacting Avid Audio Technical Support they did replace my HD Core card PCI "revision K" card by a card that is not "revision K" (case 01785880). This card swap was free of charge, I only needed to pay for the shipping costs.
Btw, I never saw the dreadful DAE error -1115