it's been some time since you both were posting on this subject. have you had any more discoveries?
in my case, i have been suffering from GERD for over 5 years.
i believe the "guarding posture" mentioned by Beth has a lot to do with my GERD, possibly even the cause. i have extremely tight and knotted stomach muscles. the physiotherapist and i believe this came about from too many crunches in the gym and sitting slumped over the computer for long hours in the "guarded posture." i also used to brace my abdominals when do heavy squats.
please drop me a note with any thoughts or updates on this subject