They're not the greatest at isolation on the TTC. But that can be an advantage as I find total isolation when walking around a bit scary. I like to be able to hear things like the subway or bus coming. On a plane, the M500s are definitely a no-go IMO.
They just sound very unreal to my ears. Bass is AWOL, treble is too much and mids are too thin. I've heard them many times on some pretty good gear and really wanted to like them...in the end, I prefer the SRH840s by a good margin.
They're in line because Tyll is the one who does the measurements. The differences are that on innerfidelity.com, they are an average of 5 different locations on the dummy's head (so more accurate there). The 300Hz square wave plots on the K812s doesn't bode well.
The MAD Ear+HD is one amazing amp with the RS1i...I'll have to slum it with my GS-X Mk2. Actually a hell of a combo...I have yet to find a pair of headphones that don't sound spectacularly through this amp.