Hey Susan,
Have you seen or tested the TX in person. If not, please do so. My wife and I originally wanted a TX because of limited space, but when we saw it and tested it we found it to be too small for even the two of us. We didn't like the fact that our legs would be crossing each other in the footwell and that the spa had only one seat with jets and the other had only the moto massage jet. We decided to upgrade to the SX and has worked out well for us. Three full seats and one cool down seat and it really doesn't take up that much more space than the TX. If you are really limited in space or have a specific corner tub requirement I'm sure the TX would be fine, but see it and test it first. As for price, I was quoted $4,700 including the ozone system, cover, delivery and setup and a years worth of chemicals. The SX with the same equipment is not that much more until you start adding the extras you need because it is a bigger tub. I added the cover lifter, the continuous silent flow pump system and spa steps. The tub is 6' X 6' and the cover lifter is a godsend. Also, the tub is 285 gallons versus 140, so I went with the continuous pump to circulate the water better and keep it hot all the time as it passes the water continuously through the heater. It's also, extremely quite. This complete upgrade cost me $5,800 instead of $4,700, and was well worth the difference. My dealer is in Ft. Worth TX and is one of the original Hotsprings dealers. Just be sure you go and see the tub you are buying and if you can't wet test it at least dry sit in one.
Hope this helps...