I will respond. I do not know the specific brands mentioned, however I am quite familiar with the BioGuard/SpaGuard equivalent to what you are talking about.
The SpaGuard product is called Optimizer Plus. The "Plus" is the floral bouquet the product has. The last store I worked at sold a boat load of the stuff. It was our 4th best selling spa product behind bromine tablets, bromine concentrate and spa lite (shock).
We were always quite clear with our customers :
"This is definitely not a necessity, its an accessory product" but I had many customers that would argue that point.
As mentioned, it will contribute to TDS. If you over do it, you can cause foaming. Just follow the directions.