I've heard the new RB-81s. They sounded nice in a 2-channel listening configuration. I've owned the RF-35s in the past. I didn't think they were too bright - just didn't live up to the hype in my listening environment. However, I really liked the sound of the RB-81s.
Another thing I noticed on the RB-81s was the veneer color. There's now a bit more red in the vinyl cherry veneer. The old cherry vinyl, was a bit neutral colored. I like the new color better. The grill structure on the new RB-81s were similar to the RF-35s I had. They are held in place magnetically.