I often work on the same CS5.5 project between three different locations.
Usually I carry the media files on a portable RAID, and the project files reside in a Dropbox folder in my documents. Even if I set up Premiere to keep media cache files next to the originals (though I prefer to have them on a seperate RAID0 drive) the whole project gets reconformed/reindexed when I open it in each new computer, which obviously takes time. Presumably this reconforming happens because the media cache database on each new computer doesn't recognise the .cfa and .pek and .ims files in the media cache folder as belonging to the existing project. Is there a way to "fool" the media cache database into using the existing .cfa and .pek and .ims files rather then generating new ones for each computer?
I migrate Projects with external FW-800's all of the time. To ease working on those Projects, I locate all of my Scratch Disk, Same as Project, and everytihng is always there, and ready for use. I do give up a bit of ultimate performance with this configuration, but never have any issues.
One thing that I do for each external is to assign the same, unique drive letter to it in the OS of each computer. Have you done this? Does your RAID box come up with the same drive letter in each computer - always?
Good luck, and with migration between computers, you might want to relocate the Scratch Disks. Please let us know if that helps.