The thing about calibrating subwoofer is that it's very hard. It's hard because it's tricky to get a good reading with an SPL meter, because some Avia disc's calibration was wrong, because the receiver plays a great roll, because the room acoustics come into play so much, and because it's hard for humans to figure out non directional sound.
Before the high end guys come out to do the calibration, ask them how they are going to do it. Are they going to just sit in one place and use RS SPL to calibrate it at 75dB across the board?
Do you have someone that can help you with a sub crawl? I know it's a pain in the butt; however, this may be the single biggest bang for the buck adjustment you can make with your sub.
You can use Flight of the Phoenix to generate *LOTS and LOTS* of LFE while doing your subcrawl. Or you can use your pink noise from the AVR.
If you get sick of trying to calibrate it, you can always buy another sub!
