I realize that this is an old thread, but I think a lot of people who are new to this topic may read it, so I'm adding my 20 cents (allowing for inflation). I have a couple of Canon camcorders in this series. The less expensive models are amazing for what they offer at their price; they're a great way to get started and to explore whether or not one is really interested in video recording.
However, their real weakness is their really poor low-light performance--where "low light" includes many average-level, available-light situations--not just nighttime or dimmed house lights. It's quite "noisy", mainly because of the very small video sensor being used (one of the major cost-savers in this line). This, to me, is far more important than whether the camera is 4K or not. I upgraded to the G21 model a couple of years ago and it produces much nicer-looking video all around.
Don't get me wrong--I think that high-quality 4K video is amazing. But I'm happy to do without it, for the sake of (relatively) affordable, high-quality HD. For me, the specification of a camera's image sensor size is more important than how many pixels per frame it records.
--best regards