We take it with us to my moms,etc. So I just thought it would be easier for her to use. In addition I felt I might have a want to just watch the video monitor and felt like I could just as well have him sleeping next to me then because I'd get about as much done ;) I also have 2 older boys and this is like what we had for them, so it's what I know and am completely comfortable with. Plus the range is great, as I could take it outside without having to have it plugged in.
I disagree that two units work properly together. I bought a second set of these same monitors to use with our second baby and they repeatedly interact with each other and lose the link to the base. I called VTech and was told that they run on the same frequency, so this will likely continue to be a problem. I would not recommend using two at the same time.
We found it to not pick up a signal when we were nowhere near 1000 feet away from our house; more like only about 200' away. Big disappointment. It wouldn't pick up the signal from our house when I was just across the street in our neighbor's house, and you lose reception even faster if you have a more solid wall like plaster or brick instead of drywall. We live in a city so not sure if there were other interfering signals from home wireless networks or radio.
I have used and currently own the Vtech tat comes with one parent unit and two baby units. Placing all units in separate rooms works fine. no issues at all. I have not had other systems at home at the same time to check for interference between systems, but these are digital, should work fine.