I have a Maxon OD-9 which sounds good but I don't like the switch that much. On reflection I might have been better off with the OD-808 just for the better feeling switch.
I've ordered an MXR Custom Badass Modified O.D.
http://www.youtube.com/watch?v=QSTy9uk_kGYWatching the videos mainly pay attention to the EQ aspects. It is pretty much standard practice to roll the gain right off when playing through Peaveys and that's what I've found works best for me too.
Hopefully it works well with my 6534+ - I'll report back on it when I've had a chance to try it. It seems like it should be able to do everything the two Maxon pedals can do and then some, but it's hard to assess it on the basis of reviews on the internet. It seems very similar to the Green Rhino but in a more board-friendly format.
I also purchased some more of those little rubber covers for the knobs for all of my MXR pedals besides the Black Label Chorus (which has very small metal knobs) so that I can adjust them all with my toes.