I play two XLRs to FOH if possible, but some engineers proved to be of the “here’s our house DI, just plug it in” kind, others get all weird if a bass player wants more than one DI line, so I have a ProDI in my bag, too. Including the ProDI, I have four DI options available (the Sennheiser has one, too), so that should cover pretty much any scenario. I mostly play in two bands with own PA, where it isn’t an issue, but it turned out to be one when I’m sitting in.
The Expression port lets you control the Dirt channel’s Volume with an expression / swell pedal, or use something like this for two predefined settings: [Invalid or Expired Link Removed]
I used both a passive Morley and a decades old Trace Elliot swell pedal with it, and it works fine. I don’t need it with this board, though, as I already have three to five different dirt options built-in, depending on how you count. The Bass Butler works very well as a standalone device though, in this use-case, I’d want a swell pedal or abovementioned EHX box.