If you are recording loud rock shows stealth and using standard small mics into any of the half-decent recorders (e.g., Edirol R-09HR, any of the Tascam decks, Sony M10) then IMHO a preamp is bulky and a waste.
You use either a battery box OR a pre, not both.
I would just buy a $39-$59 battery box and be done with it. I would be very surprised - assuming you are stealthing loud rock shows - that you'd be able to tell much difference. And the battbox will save you some space. If you do a lot of acoustic shows, classical, jazz, etc. then the ST-9100 might be more your thing. I'm probably going to get (another) one to run with my DPA 4061s, but that is for a specific application that is not stealthing loud rock shows.
Put another way, when I stealth with my $3500 DPAs, I just use a basic "battery box" (a Denecke PS/2) rather than even my relatively small Naiant preamp, because size is the most important concern. I've stealthed with it both with the Denecke and into an Oade modded PMD660 and it sounds about the same to me. Similarly, for loud rock shows, my DPA 4061s + battbox seems just fine to me.
YMMV, opinions may vary, and all that.