I have not owned the BCD, but I did have the BDA for a while. In combination with my old CD player (Marantz SACD 7001 KI) it made somewhat of a difference. I then bought the Marantz KI Pearl (the full version, not the "light"), and the difference was gone completely.
There were some m-a-r-g-i-n-a-l nuance differences, but definitely not enough to justify having a DAC in my system doing basically nothing.
So I sold it, got a good price for it too.
Unless you need more digital inputs I'd say just buy a high end CD player, for the money spent on the BDA and the BCD combined one can buy something really nice.
It is about time Bryston upgraded the BDA to a Mk2. Competition caught up big time...