As there was some interest expressed in seeing what a back illuminated chip could do, here is the result.
http://www.atscope.com.au/BRO/tutorials/backplusd5.html
The U47 chip saturated at 30 seconds (!) , and the DeBloomer plug-in was used to remove the worst of it.
With the back illuminated device there was so much signal that it was hard to pick a black point and noise be came trivial. There is also evidence of scattering/flare in the U47 star images due too much signal, hence 2x 15 second exposures probably would have been better.
Retrospectively, either comparison, while amusing, does not say a lot about CMOS vs CCD but does give good insight to "off the shelf" implementations and how that effects the performance of these detectors.