Re: Feeding the laminitic!
I'd advise you to first learn about the principles & factors that govern health & function of hooves. Arguably the best resource to start with for that is hoofrehab.com as it has HEAPS of well researched & experienced advice & info & links. With regard to learning specifically how diet relates to hooves, safergrass.org is a great resource. And for general diet & nutritional info, FeedXL.com is a fantastic service(who were - probably still are - offering freebies to UK & Sth African residents, so get onto them & make the most of it!). You can also get some of the latest research, that was presented at the Royal Veterinary College 'Laminitis Awareness' days, via Dodson & Horrell feed co if you email them & ask for the papers. Makes for some enlightening reading.
If your horse was on soaked hay by vet's orders, chances are the vet thought your horse has, or was likely to have insulin resistance problems, which make them extra sensitive to hi-carb feeds. It is a similar condition to type 2 diabetes in people & cannot be 'cured', just carefully managed to prevent the worst symptoms. Therefore I would be very cautious about reintroducing him to rich pasture, let alone 'junk foods' like grain.
I would guess that your shettie was either kept sound *despite* his diet(there are other factors to consider too), or he lived, but uncomfortably to a ripe old age. Whatever, I wouldn't base your practices on one dubious example of anecdotal evidence. Also grain is more problematic if fed in large &/or infrequent meals, so planning to feed him only on work days is potentially worse for him than feeding little & often every day. If your horse is maintaining his weight, then it's not likely calories that are lacking anyway. In fact, if he's still overweight, that may be the problem.
Perhaps he's lacking or imbalanced in his nutrition, despite the 'balancer'. Perhaps the balancer is grain based, so leading to further problems. Perhaps he's foundered(but not currently laminitic) so still very uncomfortable on his feet. Perhaps he's uncomfortable on his feet for other reasons. Perhaps it's other symptoms of IR that are making him listless. Or perhaps it's what you're asking of him & how you're riding him, or saddle fit problems or such that are the problem.
...So you can see there are a lot of considerations and possible problems to rule out or treat before considering that high energy food may be what's needed & appropriate for this horse. If you would like a critique or more specific opinion on the state of his feet, you can post some hoof pics here if you like.