Since getting my 2466/425 rig I've been experimenting with a lot of different pedals. I have found that a lot of what used to work on my Mesa Boogie Tremoverb and Mark V rigs would lose the magic on the VM.
Of course, after reading about all the other users here having luck with the Fulltone OCD I bought one and true enough it was magical with the VM. I'll get that out of the way at the start :)
Discovery #1 - On a hunch (and a good recommendation from Lance at Wildwood Guitars in CO) I tried the Fulltone Plimsoul and it really compliments the OCD very nicely. That sustain knob means BUSINESS, and there are a lot of very usable tones in that pedal when hooked up to the VM.
Discovery #2 - As I was checking out the MXR site earlier in the week I noticed this from the description of the Custom Badass Modified O.D.:
"Put it in front of the '78 Custom Badass Distortion for a slew of amp-like gain structures that won't mask your tone."
Although the '78 CBA Distortion was in my pile of ebay gear, I thought that this was worth a try. My CBA Modified OD arrived tonight and true enough when hooked together with the matching distortion pedal it just screams through the Vintage Modern. I still don't like either pedal by themselves through the vintage modern (the CBA '78 Distortion is amazing through a Mesa Mark V by itself), but I'd like to give a VERY strong recommendation to the pair of these pedals in front of a Vintage Modern.
The types of tones I was getting were very reminiscent of the JCM 800 and 900 - vintage high gain. There was everything from old Judas Priest (with the two preamp knobs in the 10-11 oclock range and the two pedals set around noon) all the way to the thrash-heavy tones of the early Slayer albums (turn the preamps up to 3 oclock and increase the gain on the pedals too). All the way through there was a smoothness that just oozed vintage-ness, there were no harsh overtones that I'd associate with the modern high-gain amp designs. Sustain was great, and letting my Les Paul feed back closer to the cabinet gave a super-rich oscillation that I haven't had out of any amp before (did I mention I love feedback?)
This was all in LDR mode between 9 and 11 on the Master Volume knob, tomorrow when my wife is out I'll crank up HDR and see how they behave in uber-drive territory. I still have a lot of playing to do with the two MXR pedals, just like the Vintage Modern they have a lot of synergies when the knobs are tweaked in just the right ways. Tonight was also maybe 15 minutes with the Strat and an hour with the Les Paul, over the weekend I'm going to see how these respond to my Jazzmasters and Rickenbackers.