I have used epitalis gel on my schoolmaster with excellent results (it is clinically proven) following vet advice. Efficacy of treatment meant now 8 other horses in my barn have since moved onto it. All horses are at differing stages of their dressage careers and vary from high level professionals to ambitiois amatuers to fun weekend riders.
Forcyte also have a powder - more expensive on a per feed basis compared to gel - at least in Australia (which contains their secret patented stuff) and has green lipped muscle and other well recognised joint supplement ingredients incl. other shellfish. By all accounts this is much more difficult to feed due in large part to its fishy smell but some longstanding users in particular (esp in racing industry where itv was first picked up in Australia) prefer it to the epitalis gel.
I weighed up the two closely when first starting and spoke to the makers - according to them the gel also has a great immediate effect (@4 - 5 days during loading stage) compared to the powder but in overall terms similar outcomes over longer term regarding efficacy.
I would suggest calling the maker and run through your questions. In Australia, they were super helpful.