Pat, you remind me I should bleed the fluid out of the rear calipers! Related to your current issue, I just replaced both front calipers as part of my Axle Upgrade Project. I first removed fluid down to the bottom of the master cylinder reservoir, then filled, then bled front brakes only.
Like you, the pedal firmed up. Like you, the HydroBoost was loud once I started the engine. I also shut back down and bled the calipers again. H-B still seemed weird. So I put the wheels back on and tried backing/stopping and forward/stopping. Seemed fine, so I drove it. I had upgraded from 2002 brakes to 2012 brakes and immediately found the pedal was OK and the braking was excellent.
So can you make a couple controlled short moves/stops and see how it's acting? Then a short test drive? I suspect you'll be OK. Seems to me we don't realize the racket the H-B makes when the coach isn't moving and all we do is focus on the noise.