I've upgraded my 2008 MacBook Pro to Mavericks and Pro Tools LE 8.0.5 runs fine with an MBox 2 and MBox Micro. Mavericks notified me that Pro Tools is not compatible, and moved the Mbox and Midi plugins to a "Incompatible Software" folder. I re-installed the MBox drivers, and now ProTools runs with no problems at all. Audio and midi record and playback is perfectly fine, plugins work and other sound sources (itunes/quicktime etc) work through the MBox.
Others have not had my good fortune tho it seems.
http://duc.avid.com/showthread.php?t=342256
It seems to be a risky process, so I'd suggest you back up everything before upgrading so if it doesn't work for you you have the option of restoring back to a compatible state.