The Bahama Spas look just like Dynasty. If so, I don't believe there is any comparison. I sold Shoreline / Garden Leisure a few years back (private labeled Dynasty) and now sell Hot Springs. The fit & finish is superior on Hot Springs, but more importantly they are more energy efficient, in my opinion have better quality components and better support from the manufacturer.
Pump size is only part of the equation. Dynasty likes to use "break" horsepower instead of continuous. How the spa is plumbed is equally important so is the number of jets and size of jets. Since you are getting this for medical reasons, you really should wet test each spa prior to purchase. Its the only way you will know which is best for you.