Just as Radial's passive ProDI is the more-affordable alternative to their industry-leading JDI, the active Pro48 is the alternative to the J48. And, just as with the ProDI, I'll mention that you get every bit of Radial's legendary rugged stage performance with the Pro48. The difference is, of course, that this model is active, running from the 48-volt phantom power supplied by your board.
I tend to favor active DIs these days, just because you never know what sorts of instruments are going to show up onstage with you. I once had a stage full of passive Radial JDIs, but then the harp player showed up with only a passive pickup. Without an active DI to give her harp a boost, we ended up putting a mic on her instrument, which at the time was far from optimal.
So, lesson learned: I make sure there's always at least one active DI in the mix. And with the attractive price of the Pro48, that's not hard to do.