Hiya, yes 30 mg was high! I had a (suppressed) raised eyebrow from another medic about it when they saw my son. But I really trusted my son's gastro - he was great.
Interestingly re the op, at the time my son had a gastro as well as a surgeon (who was involved with a gastrostomy placement) and the surgeon was massively pushing for the fundo and the gastro against it. They would (respectfully) disagree in front of me which was quite tricky!
My mum who'd been a nurse for her 40 odd year career said that was typical - 'surgeons gonna cut' type thing(!), whereas clinicians proceed slowly.
I have to say, I'm pleased my son didn't have the op. I've heard that it can cause other complications such as 'dumping syndrome'.
I'm sure for others, it's a success, otherwise they wouldn't do it. But I think the gastro (ie not surgeon) did say to me that surgeons have a tendency to overestimate the success of their ops... that they typically see the patient once after an op and the onus can be on the patient to say, yes doctor, all's fine iyswim. Whereas clinicians see the patients on an ongoing basis. My son saw his gastro for more than 9 years.
It definitely sounds like the best next step for your son is to see the paed/paed gastro and try an increased omeprazole dose if they let you, then see how that goes.
Sorry this is such a long post. It's quite identifying too if either of the (male) docs have a mumsnet habit. I try and use this name just for identifying/medical stuff though!
Best of luck. Do ask any more questions and I'll try not to be so long-winded!