I'll try to get a recording of the rig - most likely I'll take the DI right out of the BX1500. If time permits (ahem, if the wife tells me time permits - LOL), I'll try to get multiple recordings (RMP + RBI, RMP + VT, RPM + VT + RBI).
I agree that the RPM covers the lows nicely, but there is just something the RBI brings to the table that really adds some girth on the low end as well as that sparkle up top
I will definitely try VT/RBI, maybe this Saturday. And then I'll see if I can try all three.
I look forward to the sound samples if/when you can get 'em, but I know how that goes... I've been promising audio on my newest bass (got it over a month ago!) but haven't yet had the chance.

, and also record/post some sound samples.