Do you know how good or bad your water is? Do you happen to know the TDS? Some well water close to the foothills is excellent and it gets a little less good the further that you get away. I would want to know how bad your water is before I recommend one.
The most important piece is the RO Membrane. You can upgrade to a DOW Filmtec 99% rejection rate membrane that is sometimes good enough to use without DI - this is about $100 more, or so, but worth it. Here in Longmont, our TDS out of the tap is in the 30s and half of it is salt... so 99% rejection puts me at 0, 1 or 2 TDS without any DI. Again, this will depend on how bad or good your well water is.