First, I would get it in a signed contract that they will replace the ozone system with a SWG! (and if possible with a very long time limit so you can see for yourself how high the CYA levels will rise in just one pool season!)
Second, If they are installing a cartridge filter then placing a trichlor tablet in the skimmer is a good way to ruin the cart. Trichlor has a pH of 2 and when they sit in the skimmer with the pump off and then the pump turns on it is the same as pouring acid into the skimmer!
I would bet that they have some sort of deal with the manufacurer of this equipment and get some sort of kickback for each one they sell!