I'll second elvergun's endorsement.
Have been a/b-ing the Mikros 90 and the highly-touted KEF M500 for the last few weeks and in my mind there is no contest. The MLs retrieve a LOT more information than the KEFs, extend further in the treble and the bass frequencies, resolve much more thoroughly and trounce the M500 in virtually every other respect.
For classical, jazz, pop (I listened to Michael Jackson's landmark "Off the Wall" last night), world, show, chamber, acoustic, country and rock (from the 60s and 70s), the Mikros 90--in my ears--are among the best headphones I have ever heard/owned to date, and I have heard quite a few. They do require ample burn-in, 50-100 hours IMHO, need a little effort to optimize placement on the ear/head and benefit greatly from an after-market cable (I am currently using the Pipeline ET-4 to great advantage). The MLs scale up very well with better equipment. In my comparisons between the M500 and the Mikros 90, better equipment emphasized the comparative weaknesses of the KEFs but highlighted the comparative strengths of the MLs. (The KEFs are currently up for sale. The popular preference on H-F for the M500 over the Mikros 90 quite frankly baffles me.)
If you like detail, frequency extension, an airy presentation, transparency with full measure of musical transcendency, the Mikros 90 deliver in spades. Period. They also seal well and leak little--another area where the Mikros 90 easily bettered the M500.
I already ordered the used pioneer's, but I think I'm about to take a leap of faith and cancel the order to get the ML's instead.... I don't know enough of Pioneer's customer service and since they are used, I probably can't get warranty on them. Getting warranty on these and at a lower price seems like too good to pass up... I hope everything you have stated is true.