Welcome to TAD! I got M1s when they first came out. That was a fantastic speaker, a bit more transparent than an R1 as it was a 4 way and voiced a bit differently. The R1 is a little bigger and has better lower end. Unfortunately like most/all M1s, mine cracked, twice. Pioneer refunded fully the cost of the speakers. I thinks that was $45,000. Amazing. I used that to buy Magico Q5s. After a few years, I decided the Q5s were just not for me. Too dry and very fragile with the drivers exposed, and ridiculously heavy and difficult to fix (have to go to factory for anything). I sold the Q5s and TAD helped me so I could get back in to a pair of R1s. Andrew is amazing. Too bad he's not at TAD, but even without him, the support from TAD is very good. And I do agree these speakers image amazingly well. Mine are driven by Constellation Centaur monos and a Berkeley Reference DAC series 2. To my ears, it's an amazing system. I also use it two channel for my TV. No need for a sub or a center or even surrounds. On certain movies, these speakers even image behind the listener. I had a center (Pioneer/TAD center) and surrounds, but finally took them out since it was very hard to match the quality of the two channel system.
You are definitely correct that you have a fantastic system(!); I'd bet it sounds amazing with the synergy between the amps, DAC and R1s! These are very special speakers and I am glad that I took the plunge. When I look at them, let alone hear them, I know they will be with me for a long, long time! Where are you located?