So if I bin at say 2x2 this should make the chip more sensitive by x4 times.
But don;t forget you end up with an image 1/4 the size of non-binned ones. IIRC the chip in the IC is not huge, bin this and you wil end up with a tiny image.
I've never found binning images worth it. You spend all that time getting a nice hi-res luminance shot and then stretch a lo-res colour stack on top.
Further to Dave's comments, one serious knock against binning is the fact we are compromising resolution. For example, if we are imaging at 1"/pixel with 1x1 binning, we suddenly jump to 2"/pixel when we bin 2x2 ... this is a step backwards for planetary imaging, for example, where we want to oversample and pursue the greatest possible detail (ie. resolution) within our final result.
  