We just installed one from filters direct, the RD106P. It came with a booster pump, holding tank, and the faucet. We mounted it in our laundry room where I make the DI water and ran the RO under the house to the small kitchen sink faucet (our regular faucet is still well water for dishes) and our fridge for RO ice and water. I haven't replaced any filters yet.
I will say that my TDS on the DI side is running 3-6 but we haven't had time to figure out why. Could be a few things and not necessarily a problem with the unit.
One thing to keep in mind when installing at least this particular unit is that you have to shut off the RO holding tank when making DI water. I didn't at first (never read the manual) and TDS was higher. Read the manual, turned off the holding tank and now TDS more like 3, so it did make a difference. So you may need to have easy access to the holding tank. Also, I can't use the RO faucet at the sink when making DI water. I assume because the holding tank is shut off and all the water running through the RODI system is going to DI. Not that big of a deal for us. If we want water while making DI, I just turn off DI, turn on the holding tank and get it. My laundry room is just off the kitchen so everything is convenient for me, but depending on your house and where you install it, could be a problem. Just my two cents.
I was given a name to call (Russ) when I looked into these filters and he ran a company called "Buckeye Field Supply". The name has changed to Buckeye Hydro. The owner still answers the phone I believe and knows more about water filtration than I ever wanted to learn. I remember he was a biologist, diver and a reef keeper. Visit his site and read what other customers say about them. It is worth the phone call. I know they have a home & reef system combination. Cheers.