The only alternative I've heard of is the CT scan. The inability to have an MRI is a definite problem with the LINX. Have you considered the Nissen fundoplication? Since you have a preexisting condition and KNOW you need periodic MRIs, it seems that it would be the best option. Don't believe the hype. It's a proven (gold standard) fix for GERD, and most people are highly satisfied once they've completed the healing period. I had it four+ years ago and am thrilled with the results.
BTW, from what I've read, the risk is more than just demagnetizing the LINX:
From what I understand, they're trying MRIs at lower levels of power as they continue LINX research, although there is nothing at this point that would allow MRIs on LINX patients. There is a lot not yet known about the LINX procedure in the long-term. It's still in fairly early stages of implementation.
Good luck making your decision!
Nissen Fundoplication 2/09
"Whatever you fight, you strengthen, and what you resist, persists.”
“Worry pretends to be necessary but serves no useful purpose”
“Accept - then act. Whatever the present moment contains, accept it as if you had chosen it. Always work with it, not against it.”