I heard both speakers but in different systems with different room acoustics and different upstream components. I remember thinking the M5s were more listenable -- smoother with more body while the Q3 speakers were faster, more detailed, but one or two clicks toward center of gravity in the upper registers. Disclosure, I own S5 speakers (could not be happier with them...wonderful on every dimension that is important to me). I had one interaction with A Wolf at Magico and he was very responsive and friendly. I admire a man who can create something so wonderful... nothing but compliments from here. And people who work for Magico (e.g., Irv Gross) are exceptional and consumer + music focused.
Magico Comparison
I noticed that there is currently for sale a pair of Q3's for $23k and a pair of M5's for sale for $22.8. That is quite a discount from list on the M5's which retailed for $89k and a reasonable reduction on the Q3 list of $37k. Has anyone listened to both of these speakers? I think the Q3 sounds really great but I also have been very satisfied with my used V3s. It will be interesting to see if the tremendous depreciation that marked the previous generation of Magicos (Mini I and II, V2, V3 and particularly M5) occurs with this new generation of CNC machined enclosure units.