Some horses will be ok doing 3" at 20 but I think that's pushing it. I don't know how much longer he'd be able to do it well. What I don't like about it is that the horse isn't showing 3" now, it was in the past. I would think reconditioning a 20 y/o to do the 3" would be hard. But if your trainer likes him, the vet oks it, I say go for it! You'll probably be paying for Adequan and supplements but that's normal for the older guys. I assume by the ad you're leasing and not buying as well, so if it somehow doesn't work out you can end the lease..?