Repeat, I have the spa monitor on my Marquis tub. My sister actually purchased it as a Christmas present for me. I love the convenience.
I can adjust the temperature from the house and I know pretty much what is going on in the tub at any given time. It is nice knowing if there is a problem in the winter, you have an alarm system to alert you.
There is one thing that I would caution you about.... I was getting some interference from my Radio Shack 5.8 ghz cordless phone...the alarm would go off because the remote would lose contact with the spa. When I finally realized that the phone was the problem and removed it from the room, everything was fine. I would pay $200.00 for this option.