I have a BDP-2 with the upgrade audio board (same as used on the BDP-3). It works very well as a Roon endpoint. I haven't even tried the Manic Moose software since I've been using Roon since before I got the streamer. The only other streamer I've compared it with is the Node 2i, and the Bryston is a clear step up (lower noise floor, more precise imaging in particular).
If you are just looking for a Roon endpoint, then the BDP-2 with the upgrade audio board is a nice choice. You can probably find one for under $1K. The BDP-3 has a more powerful processor, which makes Manic Moose run faster, but has no benefit for Roon playback quality (according to Bryston).