If you ask Jeff Sipe directly I'm pretty sure he won't allow it. I've been told no on board patches by him a few times. If you don't ask him and the sound guy gives you one then thats a different story, and probably the way I'd go.
I'm don't know anything about the H1 but an attenuator for SBDs is probably a good thing to have.
Okay, just realized this is today and you're probably already there. I would say just go to a music store, radio shack or guitar center or something and get an attenuator.
Looks like a pretty nice line up though. Just saw Fifth house yesterday. CCL then Jeff Sipe, not too bad.