Magnepan new 20.1R and older 20R, sonic?

The 20R sound best bi-amped with an active crossover.
The 20.1's sound better with a single amp through the passive crossover.
These difference might make the choice for you..

If the difference between the 3.5 and the 3.6 wasn't enough, then you might want to look at your upstream hardware and room acoustics.

Terryakhan, I have in my system MG-20's and very seriously listened to MG-20.1's and found the difference between the two speakers to be very slight in all sonic areas. The only difference I could discern, maybe, was that 20.1's would play somewhat louder with greater clarity on huge dynamics, but that was about it. So, I kept my 20's and invested my money in the rest of my upstream components.