Bel Canto 300M versus 500M for center channel

I have been using a Bel Canto 300M for my center channel (a Kef 204c) quite effectively. However, I recently upgraded my R/L speakers to Verity Audio parsifal encores (driven by pure class A monos) and feel the center channel has been left behind a bit by my main speaker upgrade.

On my concert discs with lots of vocal information on the center I am missing some "musicality" relative to the very natural sounding Verities. The Kef 204c will absolutely stay (I would need to spend a small fortune to get something better), but I could consider upgrading my 300Ms. The obvious candidate would be the ref 500m. any comments on this? Anyone compared the two. Would this make a material impact? I am in no rush and would wait for a used single unit to hit the A'gon or eBay before making a move, but if one does show up I want to make an informed buying decision.