I just installed the optional phono stage in my BP-17(3) and I have to say it is fantastic. It is the exact same MM board that goes into the Bryston BP-2. (One small difference is that you cant change the mm capacitance loading the way you can in the BP-2)
Got it on a whim to try it out because the Stereophile review was so good. From a sonics standpoint -- compared to cost no object phono stages, I'd rate the board as very very good to excellent. IMHO It is so good that I plan to add a step up transformer for my moving coil, sell my outboard phono stage, and call it a day.