Though I still have the BMR with rotated tweeter, I did replace it in my rig with an upright BMR.
There is no discernible difference in performance.
Regarding the Song Center RT, I met a guy who had this in his rig and loved it. He was using it with Phil 3s. The voicing of all these speakers is largely the same, but if you can do another BMR on its side, I think that's best.