I have not listened to the Rega Brio-R but have owned the Elicit, the predecessor to the current Elicit-R. If the Rega house sound remains fairly similar, the words I would choose to describe the Rega would be "warm", "rounded", "lush" and "sweet" as opposed to Naim's "exciting", "detail", "separation", "attack", "timing" etc.
Both can sound great and one can sound *better* than the other depending on listening taste and preferences, not forgetting the speakers that will be matched to the amp and other factors which include the setup, room acoustics etc.