It's entirely possible that the RS6's sound closer to the M50's as they are similar in design...2 1/2 way vs the 3 way design of the M60s and M80s. Regardless, they are an enjoyable speaker to listen too.
I just felt they sounded simialr to the M60s. I think as Ken said it really is splitting hairs as to the sound of each, but I know I was taken aback at the less forward sound of the M60s compared to my M22s, but now that I have heard the M22v2, I think the M60/M22 are very close. My M22s Ti's are closer to the M80s forwardness, which is why I ended up with M80s and most likely why I feel most other speakers sound closer to the M60's sound except but a few.
