OK, I'll recant a bit. Now that I'm sitting in front of them, listening to Leo Kottke.
Vocals and beautifully recorded 12 string is knocking my socks off.
Top-end is smooth and extended, yet not "hot".
The soundstage with a tube amp driving them is commendable.
The failing is in bass below 70Hz on the M52s.
With a very tight solidstate amp I had issues.
Listening to the DVD-A of American Beauty, Phil was all vapory subsonics and string ticks.
With the tube amp, Phil is present and sounds more normal, but slightly down (probably closer to the intention of the mix, I'll guess).
Construction on the M-series is very heavy, thick MDF and quality drivers.
Those prices are seriously good !
I would say that if you are seriously into rock with heavy kickdrums and big bass, you may find them lacking.
Feeding them with a tight SS amp, you may not be happy.
Overall, I think that you are dead on, in terms of "bang for the buck."
Missions have a serious following in the UK, I am told.
Maybe someone from the other side of the pond can jump in and let us know if that's just sales hype.
Don't ask me about the 5.1 systems, tho'.
Not my bag.