You had a thread a couple of weeks ago stating that you had both and wanted to know which to sell. Why can't you listen for yourself and decide which you like better? I don't know how someone here is supposed to tell you which one you prefer.
I would expect that the optimal set up locations in the room would be pretty different for those two speakers. The Mirages need to be well out into the room, similar to Magnepan or other planar speaker. If you can't move them out from the front wall about 4 feet, you will never hear them at their best and should probably move on. I owned the M-5si for over 10 years and liked them alot. The OM-10 is a descendant of the M-5si and should be significantly more extended in the bass. I have never heard the OM-10, but would expect some resemblance.
