I disagree with your disagreement 
It seems an accepted fact that MPS adds to TSD, but some people add 3 pounds of PH balancing chemicals to brand new water! I use Sea Klear MPS (no, not a paid endorsement, but it should be 
) It has no buffers so you can use 1/2 as much as other brands. I've found that when water gets cloudy MPS brings it back faster than a shock level of dichlor. I'm regulary getting 3+ months out of my water, I use the MPS every other weekend, or if I get cloudy when I've ignored the tub for a couple of days.
I wouldn't add MPS after every soak the way she said her dealer said to. (Mine told me the same thing, they were selling the Rendevous brand - Renew, and it is expensive)
I also use MPS to shock rather than dichlor. I like the fact that I don't have to wait a day to use the spa and from what I've read, it does a more complete job of oxidizing than does chlorine. It is also no fault...you really can't screw it up. If you don't add enough chlorine to reach breakpoint chlorination, you haven't shocked where as if you add too little MPS, it will still burn up chloramines; if you add too much, it stays active in the water until it finds something to oxidize. Shocking with dichlor will raise CYA levels very high while MPS will add to TDS, so a tradeoff here...but if you change water every four months or less, there should be no issue with either. I shocked with dichlor for a couple of years and then made the change and have been very satisfied.
