MS's own defrag doesn't show red bits, doesn't show much at all actually.
I have actually been using one version or other of Diskeeper since 2001. During that time I can state, quite positively, without going into detail - it helps, it really does.
It
is a somewhat subtle help, it's not a huge thing, but it definitely helps.
And I'm not totally sure about this, but I believe MS's defrag facility is actually provided by Diskeeper - it's a dumbed down version. Can anybody confirm or deny?
And as I mentioned in the review, once each disc had been defragged, the auto-defrag feature within Diskeeper didn't hit my system's performance and my HDD led wasn't on constantly as described here in this thread.
I also pointed out in the review that running BOINC will turn off DK's autodefrag but in my opinion for £23.50 it's still worth having just for the manual defragmenation, which means, imo, that auto-defrag is
not the whole point of the software.
The whole point is defragmentation, the auto stuff is just a bonus, or pain, if you're so inclined

You can use it or not use it, it shouldn't be
too influential if you're thinking of purchasing.