CK,
One thing with the BC refs is they have very high damping factor, which I could imagine might make speakers that do not require high damping sound somewhat tighter or leaner perhaps.
The OHMs in my system are renowned for drinking lots of power and current and also to sound best with high damping, so the BCs were a very good match on paper and have panned out equally well in practice luckily.
I run a pair of small Triangle Titus XS monitor speakers off my system also. These are more efficient and easy to drive, more tube friendly speakers. The high damping and current may be a bit of overkill with these in that sometimes I detect a touch of leanness with these perhaps compared to some other amps I have used.