Just a quick two cents...a few years back, when I had my horses all on SandClear, my vet informed me that bran works just as well if not better. You cannot feed it more than a couple of times per week or it loses its effectiveness (as well as the calcium/phosphorous ratio). He sent me a copy of some studies that had been done on this issue. It has been a few years now, so I don't recall the details.
If the SandClear is working so well for your previously neglected horse, I would stick with what works for him!