I've used the entry-level Chatterbox FRS system...
They worked well, but only after we took some time to get everyone in my riding group "dialed in." Some had the mic too close, some to far. Unfaired bikes trip the VOX very easily, and there's nothing worse than hearing someone else's wind noise in addition to your own. Plus that "takes over" the channel so you can't communicate anymore.
Also, we had to learn to activate the VOX with something like "uhhh.." before speaking, or it would cut off the first spoken word or syllable.
We tried push-to-talk and preferred it, but another button on the bars and more wires makes this less convenient than VOX.
However, I cannot recommend the Chatterbox due to poor quality. My group of 4 has gone through 8+ units. They stop working, knobs break, etc. This, and the amount of adjustment describe above required to get them to work well, has caused us to abandon them altogether.
I *do* however like their rider-to-passenger unit. It's wired full duplex, not VOX, so it sounds like you're talking on a telephone....