Whilst the models on the B3 are pretty good, they don't sound the same as the pedals they're based on.
The Bass Big Muff model is very close to the EHX pedal, but there's quite a difference between the ODB-3 pedal and the modelled version.
I kept my BBM when I got the B3 and have since picked up an ODB-3.
I have said, in a previous thread, that in a full band situation you'd not notice the difference. But there's certainly a difference in the ODB-3 .
As I use the B3 on one loop of an LS-2 the tuner mute is pointless, so I still use a Polytune at the front of the signal path.
The ODB and BBM are in the other loop BTW, both loops run at the same time.