I think Copperpoxy would be more popular if it were any good.
The only experience I have with Copperpoxy is helping someone to apply it to their boat. The stuff is real thick and gritty. You can't get a nice smooth bottom with it. Maybe if you sanded it down, which would be a waste of costly product.
The method you're using with epoxy and copper powder sounds better.
Around here, boats are hauled every year so hard growth is not a problem. The problem is slime buildup. The slime-blocker paints don't stop it. You just have to scrub the bottom once or twice a season.
Its amazing how much faster the boat moves after you give it a scrub.