Next week our band will be rehearsing in a studio that is both a recording studio and a rehearsal studio.

Apparently they can record your rehearsal and give it to you on a CD. I'm sure this would cost extra. The recordings I make are disposable - I listen once, maybe twice, just to see what's working and what's not.

In general, would it be considered poor form to record the session yourself on a portable recording device?

I have zero experience in studios and I'd rather not irritate them our first time out.