The first time I tried 2-way radios at WDW they were an inexpensive set. They worked OK but there was a lot of people talking on the channels.
Last year I took a new pair of Motorola's. This pair had 99 channels, and privacy sub-channels. Basically it took each channel and broke them up into multiple sub-channels. When we used them, we didn't hear any one else when we were talking. So that worked out a lot better.
However, always take the rated distances with a grain of salt. Also, always have a verbal fall back plan, in case the radios don't work. I say that because we experienced very sporadic results in the park. For example, in the MK we could talk from one land to the next. However, a couple of times we couldn't communicate, even though we were very close. One time we stopped for lunch. My DW sat down with the kids, and I got in line around the corner. I wanted to clarify the kids lunch order, but I didn't want to get out of line. No problem, I thought, I'll just use the radios. They didn't work, even though we were in the same place. Another time, I was trying to get my DW, but ended up seeing her, before I could raise her on the 2-way radios.
My suggestion would be to take them to the parks, and use them. Just don't count on them working 100%. If your going to split up, always arrange a meeting place for later in the day.