My horse at the recommendation of our vet (in Wisconsin) had been on Cosequin ASU for years due to both hock and coffin bone issues. For a period last year, I took that out of his supplement routine and a follow-up visit from a different vet had them commenting to me to get him back on it. Within a relatively short window after getting back to our maintenance dose, we saw a difference.
I know that Cosequin ASU PLUS has the same level of HA in it that the product you are using. If you like the people at SmartPak, why not ask their feedback on what to use to bump that up.
We also supplement with Farrier's Formula 2X. Because we feed so little grain/feed (our boy is an EASY keeper) and use Coastal hay, we added GroStrong Minerals as free choice to get his mineral/vitamin levels a boost.