Since no one is responding, I'll share my experience with AMT BC-1. Yeah, it's not BDDI, but it's in a similar voicing group IMO (tube emulation).
Few words about how I see each pedal first.
BC-1. Massive saturated lows, scooped mids, clanky high mids/highs. Pretty much the same goes for BDDI.
B7K. Neutral non distorted or saturated lows (I guess they split them before distorting the signal), really
pleasant mids (drive is pretty heavy and it produces great sounding and smooth signal).
Lows on B7K were somewhat lacking for me, so I tried running B7K into a clean channel of BC-1 for some tube-like saturation.
I didn't really liked the result. Yes, it had better lows indeed, but it destroyed the things I liked about B7K at the same time. Nice and even mids became scooped and highs became harsh.
The result may vary depending on the amp/cabinet/bass, but in my experience it was "okayish" at best. I tried combining strong sides of both pedals, but neither of them really shined in the end.