Reality is the majority of vets know little to nothing about actual nutrition, bioavailability of various ingredients, etc. What they DO know are products that tend to be front and center in the vet circles, and the Platinum Performance line of products is one, because they are “founded in veterinary practice”. That doesn’t have any bearing on how well a given product can do its intended job. I mean, lots of vets still recommend Omolene 300 for foals because it’s by Purina, it’s a growth feed, they likely got some nutritional training from Purina in school, and they have no idea that even though it’s not new info, high NSC diets are strongly linked to DOD issues in foals.
Even that study isn’t well done, if for no other reason than there wasn’t any control group.
Given that the amount of each ingredient in these products (Relyne from Hagyard, and GutX), not hard at all. Well, that’s all relative right? You CAN get beta glucan that’s derived from various sources, you CAN get HA, and if you have the right equipment you can measure out the doses either product uses.
As for the OP’s original question - the only way to know is to try it on your horse at this point in his life. That’s the only answer to every single joint supplement out there. Even for the ones that tend to produce the most results, for every 1 horse it works for, there will be 100s of horses for whom it didn’t work at all.
Me, personally, I go with Actiflex 4000 as a starting point. Liquids are most bioavailable. It has green lipped muscle in addition to others common joint-supportive ingredients. It’s still not a cure-all, but it doesn’t break the bank, and it does help a lot of horses (and also doesn’t work on 100x others LOL)