Releasing Foot Brake after Slides are out?

I hope you're not talking about a MH with an air brake system. Anyway, I'd keep the parking brake set. If you were to release the brake there is the possibility your MH could move slightly and maybe damage your levelers. BTW, most levelers will retract when you start the motor and put the tranny in drive. I had to do that on a brand new Allegro Bus, at work, because I didn't have a clue where the level control panel was (it's now on the glass digital display panel).

So there's some replies on leaving the brake set, now I'd like to hear your reason for not wanting it set.