I just got my copy of TTP 5.0.1 in the post. It being v5.0.1, I'm a little scared to use it - oh, the 'irony'!

I'll tell more once it's in there and doing stuff.

Well, for one thing, this time round they've very sensibly opted not to copy any of the Time Machine code over to the eDrive (a cut-down copy of OSX on another volume from which you can run all the diagnostics and tools against your startup volume) - this prevents unfortunate incidents with TM trying to back up the new volume over the top of your old startup backups...

It's easier to use, and faster - especially at the whole file/space defrag thing. Now the file defrag and space defrag are divided into two discrete modules, so you do the files first and then tidy up the contiguity of the space.

I've always used TTPro in emergency or suspect situations booting from the CD/DVD. I also found that the eDrive is useless when the drive it is installed on fails.

For sure, the eDrive should be on an external drive - mine is on the same FW800 drive as my TM backups. It's much faster booting up that way than from the DVD, and you can keep the OS up-to-date on it that way.