Difficult to quantify and it will also depend on the size of the CCD and the amount of pixels of each of the 3 CCD's compared with a camera with one CCD. In a 3 CCD camera, the incoming light is split in the three primary colors by a prism. First some light is lost through the prism and secodnly the amount of light on each of the CCD's will only be a third. The effect of less light is compensated by using less pixels per square inch, so the sensitivity of the CCD goes up. In general the images will be more sharp. Because of the loss of light, an issue to be aware of with 3 CCD cameras is that they are not very good in low light cirumstances, so you will need a video light much quicker than with a single CCD camera.
Normally, I would say that 3CCD is certainly better. But TPFKAS is right, with a new crop of very small 3CCD cameras coming out (many by Panasonic), you really have to look at the pro's and cons. There's certainly no question that prosumer level 3CCD is far superior to anything consumer. It gives you much better color representation and sharpness -- images don't look nearly as muddy. I agree with what's stated above. Also, keep in mind, different brands of cameras generally have separate looks. Sony is a bit cooler, tending to have richer blues, and it seems Panasonic is a bit warmer. Definately get your hands on a camera and check them out.
they don't make them anymore, but you can find a used Sony TRV900 around for under $1000. EXCELLENT 3 chip prosumer camera.