An ethical show salesperson will return a commission on a canceled deal when it is within 7 days of the event. Then the dealer can refund you. On the other hand, you have a 3 day right of recission when you buy at a show.
Your only protection is if you made your deposit with a credit card.
Hot Spring spas have been chosen by more consumers than any other brand. Typically they are considered a top quality brand.
Just as with any other appliance there are subtle differences from manufacturer to manufacturer; from brand to brand.
To actually answer your question, Hot Spring is the only brand that filters 100% of the water 100% of the time. Every other brand has bypasses when your jet pumps are on, meaning some of the water is not being filtered while you are using the spa.
"We ended up getting a MasterSpa with similar specs"
I am sure you will be fine with your tub. the D1 dealer should thank you for the opportunity and move on. However, to say you got a Masterspa with similar specs is like saying you were looking at a Lexus and chose to get a Chevy with similar specs.