My experience with this new Beta is ................ ummmm Ok so far, but I am not really comparing it to the Vista Defragger as much as I am comparing it to the PerfectDisk 7 defragger I use in XP........... if that makes sense.
Anyhow, I defragged TWICE in Vista using DK10 and the best fragmentation level I could get was some files with ~85 excess fragments or so, which was better than after the first DK10 defrag, which had me with a few files of over 130'ish fragments, but still far better than without defragmenting at all.............
After the SECOND round of DK10 defragging, I rebooted to XP (I'm there now) to defrag this Vista drive using PerfectDisk-7, which I did and here are the "After" screen shots:
Ok, with this shot, as you can see, it is the "Summary screen", but a few things "STAND OUT" if you will........

Like the almost 650 excess fragments in the Metadata..........

Wazzup wit dat???
On to the next one...........
Well dang it all........ there's that rascally HIBERFIL.SYS file I can't seem to get rid of in Vista......... 2+GB in size, but thankfully only ~30 or so excess fragments........
Last one for now.........
Ok, so apparantly Metadata files not only hidden, but cannot be defragged, and I'm OK with that....... EXCEPT that one of the files has nearly FIVE HUNDRED EXCESS FRAGMENTS and the other one has nearly ONE HUNDRED AND FIFTY!!!
Is there any way possible that MS with this glorious new OS could reduce the number of fragmented files that we as users cannot "UN-FRAG"???