I have used both. I actually started using Smartflex Senior but had trouble getting my horse to eat it. Tried both pellets and powder. I did like how she responded to it. I like the Devil's Claw for managing pain which arthritis is. I switched to Actiflex 4000 and I do not have trouble getting her to eat it because I just syringe it into her mouth daily. I have not had any noticeable changes in her. She is also on MSM and Flax just to cover all bases. I also injected her hocks which probably made the biggest difference. You could try adding Devil's Claw or the B-L solution and see how she responds. If you like the response then switching to SmartFlex Senior or adding Devil's Claw might be a good idea.