There is no such thing as a water saver. Membranes must be flushed or they foul and need replacing, there is no way of getting around this. I wish they would do more research before taking peoples hard earned money. Think about it for a minute, you are taking the concentrated brine out of one membrane and putting it into another then trying to further concentrate that brine by reducing its waste ratio. It doesn't work for long.
The ONLY way you can get away with reducing the waste for very long is to have softened tap water with an extremely low TDS of say 50. At that you could probably get away with 2:1, if the TDS is higher than that but it is still softened water you might get by with 3:1 up to say 250 TDS and anythung higher than that or if it is not soft or softened water you need to stick to 4:1 or the cost of membrane and DI replacements far exceeds any potential water savings. BRS has not been around long eough to figure out what all the other vendors have known for decades I guess. I love BRS chemicals and have lots of them in up to 5 gallon bucket sizes but they need to stick with that and leave RO to the experts. Haven't you ever wordered why all the other RO vendors don't offer something like that? If it were that easy they would all have been doing it 30 years ago, none of them are dummies.