Camcorder LOW LIGHT modes

What is the quality of the low light (night shot/view) modes on the
following video cameras?

Panasonic MX500A (PV-DV953)
Sony TRV80
Canon MVX3i

Does anyone know what shutter speeds are used?

I have previosly had a Panasonic NV-GX7A, and the night view mode was
useless due to slow shutter speed.
Does Sony comprise colour depth to allow a higher shutter speed?