I didn’t read through this whole thread - I’m sure @BoyleHeightsKid has ya covered
but just a note to say that I do not personally use pour-in pads because they continue to cure over time, so what starts out as reasonably soft will continue to get harder and may be more pressure than some horses can take. I prefer the softest DIM I can find - sound horse extra soft or equilox soft are both good - and they will not harden over time.
Something else to consider with packing is that not all horses like packing in their collateral grooves, and may respond better to a pad than a pack. In my experience, if a horse’s heels are super contracted (which almost always goes along with thrush in the central sulcus), the pressure from even soft DIM packing in the CGs can be way too much. Thrush treatment and a padded boot/cast/composite package is usually the way to go, depending on what kind of protection is needed. Once heels have started to expand and thrush is more under control, that’s when I find these guys often (not always, of course), start to go “ahhhhh” and enjoy the support in the CGs. It’s like they need that baseline of slightly improved caudal hoof health, and then the stimulation of support to the internal structures feels good. They’re all individuals though, so being able to be flexible and adapt to what your horse tells you feels good is key.
*a disclaimer that I’m not yet a pro. I’ve rehabbed a few personal horses and have been trimming, studying, and doing my own hoof care for a few years. I’m now actively in the process of transitioning my career to hoof care and am taking on some clients. So these comments aren’t coming out of nowhere, but you’re also not talking to a seasoned pro.