Logs would be nice, but since vengeance doesn't actually show up in the combat log, they wouldn't be the best evidence ever. At best, you'd figure out what you already know from watching the video posted earlier.I'd like logs, thanks.
If *you* really want it changed, get a brewmaster friend to soak a magic attack, using Zen Meditation, Diffuse Magic, and Fortifying Brew as it's going off (I think those are all off the GCD, so they should work together in a macro). Should get 125x as much vengeance as intended (assuming unglyphed FB, so only 20% DR. If it's glyphed, it'd be ~133x as much vengeance). Best part is, you can do that at 90, regardless of gear .
Yes, it works with any damage reduction. I can replicate it pretty consistently as a bear; timing it's a little rough, but it's not hard to tell the difference when you succeed. I'm just assuming that stuff about Brewmasters, mine's 61. But in theory, it should work.