Hi Peter,
I have the Mk1 MR1's (as part of my test setup) and the B2 plays through them via Bluetooth (just done a test). It also appears to reconnect automatically if the MR1's are powered off and on again.
So no reason to think the Mk2 MR1's won't work.
Haven't checked the range as my MR1's and B2 are next to each other on the shelf above my desk.
I think the MR1's sound great with the B2.
Paul
Brennan Support.