Hey Josh,
You should first try to investigate the cause of the saturated stars. Activities like combining subs using the sum algorithm will cause stars to reach saturation, especially if using a 16-bit FITS with a 65k count limit. Floating fits does not suffer from this problem. Usually however the data is automatically scaled when saving to a 16-bit format so its not a big issue but something to be aware of.
The issue with using pixel math as you suggest is that it is applying it to every pixel including that of the extended object. Thus, you inevitably need to use non-linear data stretches to pull the extend object out of the background count whilst still managing the star intensity. It doesn't get around the problem.
Using DDP is a great way to get good stellar profiles too. Other than non-linear stretches, you could also try taking short sub exposures just to bring out the stars and merging this data with the longer sub exposure master. Takes some practice but can be achieved in Photoshop with relative ease using lighten mode and keeping the extend object stars layer dim.
You may also wish to check out this post on managing stellar profiles -
http://www.iceinspace.com.au/forum/s...9&postcount=40
What pixel math is great for is normalising masters of narrow band data so that the applied weighting on the combine can be correctly performed. If a master has a bias i.e. overall brighter than the other masters it will dominate the scene. By subtracting the a value from this master to match the background of the other masters, you've got a much better chance of reasonable result. A 4:1:3 weighting for SII:Ha:OIII respectively is often a good starting point following normalisation.
