To start: ECO smart is NOT a saltwater chlorine generator. It is a metal introduction system that will pollute your water with metals that will prevent algae but eventually stain your brand new pool. You also must continue to use chlorine to keep the water safe, which since the PB decided you don't want an SWG you'll have to add another way. You know, that thing he supposedly doesn't want you to have to do. Tell that pool builder to bugger off with that piece of junk.
Not to get too much in to "chlorine smell" and why it's neither chlorine nor has anything to do with the chlorine introduction method, but long story short is that following TFPC levels in your water will prevent this. Following it will also allow you to use an SWG just fine without extra chlorine addition. That PB likely doesn't properly size the SWG to the pool, nor recommend the proper CYA level to protect the chlorine that's produced from burning off in the desert sun. One of the keys to selecting an SWG is to take the size of your pool and pick an SWG designed for double that size. That allows you to run it for a shorter amount of time, gives you wiggle room if you need more chlorine, and if the water is properly managed the cell should last twice as long as a smaller one.