Dubin you bet.
I listen at mostly low-med level, in a smallish room, which can be treated at will with various bass traps and foam panels. I prefer less treatment for acoustic and aesthetic reasons.
I am searching for smooth bass integration. I am not sure why, but I am very critical of inarticulate bass.
The B3 is the most seamless integration I have ever had. The R205 just slightly less so.
They both liked different spots in the room but once set up properly the B3 presents the lows with more authority without calling attention to itself.
Volume levels seemed similar though I don't listen at loud volumes often. Albeit the B3 energizes the really low notes better.
Overall I would sum up by saying, The B3's advantage is clearly in its ability to disappear into the system and do its job. For me, that is to pick up where my mains leave off and no more.
I use Merlin TSM-MXe's. In my room they drop off pretty steeply below 38hz. I have a slight bump up around 54hz (I have a Velodyne SMS too, though it is used on an NHT setup in another room)
So far I am completely satisfied with the Merlin and B3 combo.
I have the crossover set at the next to lowest Xover point so that it is well rolled off before the mains kick in.
Hope that helps