I thought about this a bit, and then tried looking up technical drawings of the rotors for comparison. Surprisingly, Brembo had a tech drawing on file for the Ody, but none for the Pilot. I still have some NIB Centric rear Pilot rotors here that I haven't had a chance to install yet due to major unexpected life changes (probably will have to be a project for next summer ) So, I pulled one of them out, dusted off the digital calipers, and started taking measurements and comparing them to the printed out drawing of the Ody rotor.That’s as much information as I found. My concern is contact surface area of pad to hat. Even at a few mm different diameter, you’re substantially reducing the “shoe contact patch. So although it may work well enough to stop the van from rolling when removing a front tire, it will NOT work in any emergency situation, ie. loss of brake fluid, et al. Yes, it may eventually wear in to fit, but again, if the lining is 3 mm thick and the difference between diameters of the hats are 2 mm, you’re completely worn through to shoe metal before you ever make contact with the active (wheel cylinder) side of the shoe lining. Depending upon the relationship of the passive (hinge) side, that may not make contact either or more likely be the only place that ever does touch the hat.
I am currently researching rear brake options since my backs are shot (including calipers) but since this is all (brake upgrades in general) in the name of safety, I can’t see the logic in accidentally undermining the effectiveness of the emergency brake system. It would be prudent for someone who has done the rear mdx swap (and users/has used the e-brake) to pull off the rotor and inspected wear to evaluate function.
Turns out, the rotors are basically identical dimension wise except for the OD of the swept area (the whole reason for upgrading them). Everything else matches (within a small margin of error, say +/-0.3mm, give or take). In total, I verified the thickness of the swept area (11mm), the thickness of the mounting surface (6.2mm) the depth of the hat (43mm), and the total rotor height (63.6mm). The bit of undimensioned space between the inside of the mounting surface and the "ceiling" of the hat works out to 14.4mm per the drawing, and (as you'd expect) this was confirmed with the calipers. The little offset between the innermost lip of the rotor and the back of the swept area is about 3.6mm, for anyone curious. I also confirmed the 210mm ID of the hat; however, I had to use a tape measure for this, since my calipers top out at a little over 6". So, no worries about using Odyssey parking brake hardware on the Pilot / MDX rotors
I'm not sure why the shoes are different between the two though. Maybe something to do with packaging, or stopping power requirements based on expected vehicle weight?