Last summer I had to choose between a new 2012 Aria and a used 2007 Envoy. I had the same concerns as you and wanted the strongest jets for my back issues. I ended up going with the used Envoy which saved me approx 50%. While I wouldn't mind if the jets were slightly stronger, I haven't regretted my decision. I find that after 10-15 minutes, the moto-message has satisfied my back. To my surprise, I actually spend the majority of my time in the non-moto-message seats. The only thing that bugs me a bit about the Envoy is the diverter valves. I'd like to sit accross from the foot jets and also have the back jets on - unfortunately it's one or the other at a time.