I would try to change the alkalinity of his diet, if you can. Less acidic fruits, for a start, and increase the veggies and legumes. We used cloth on my dd for 3 yrs., w/nary an accident. My son was potty learned early, but we never had an issue with him or his blow outs in cloth, either.
My never fail system: daytime: Motherease diaper with one fleece(hemp backed) extra laid inside and a super whisperwrap cover like one of these
http://www.babyearth.com/bummis-super-whisper-wrap-diaper...
At night we used wool covers like these
http://www.diaperjunction.com/kissaluvs-wool-diaper-cover...
and I used a full prefold diaper inside a mother ease diaper. Just fold it into thirds, lay it inside, and then snap up the ME diaper. I used this system during the day too, if I knew we were going out for a few hrs., and wouldn't have a place to change wet diapes (obviously not for poopy ones, those are deal breakers lol!).
My little guy loved the longies, too http://www.diaperjunction.com/wool-longies.html
You can find these all over the web, even 2nd hand on ebay. Diapers are $$$ and if you are not planning to have more kids, or are short of funds, you should get them 2nd hand. MotherEase does have it's own forums where you can find them 2nd hand. I recommend getting about a dozen of their one size (not all in one or Sandys), which are snap together and VERY easy. MY husband loved these. And get the bummies super whisper wrap covers - also very easy, super easy and fast to wash/dry, and they WORK. Wool covers, you'll need at least 2, but 2 should do it. If you get used diapes, you can do the whole thing for about $125 or so.
http://www.mother-ease.com/wwwboard/messages/Default.asp/... This is the sort of thing I'm talking about! That's a great price! Also, if you ever get to feeling crafty, these diapes do dye beautifully. When I was using them I'd dyed them all colors of the rainbow and tie dyed some too!