I too am a Tech 21 player. I have used the RBI and RPM for many years. The RPM, a rack mount Para-Driver I understand is my favourite. I like the sweepable mid control. I use mine as a "boost, enhancer, or ….." to my GK 700 RB II in my rack system.
When I use my SVT I don't use it.
I also used the DI out of the GK, post eq with these pre-amps. But at a flyaway show once, the SVT rig there was sent to FOH thru a Radial JDX - 48 DI. This unit was designed I think at first for guitar to use instead of a mic on the cab. Version 2 I'll call it, has a few features for bass. But yea, like a mic on your cab or "post eq" signal. Every FOH tech has loved it. So….. sorry too many espresso's. Para-driver or RPM, I'm with ya.