So this was an interesting experiment...
I've applied the same processing steps to both the original stack and a fresh stack of all my frames, and I'm not noticing any behavioural changes in the stars, just a bit of enhancement in the colours, notably in the nebulous areas as I was hoping...
- stack as above, 15x 4 mins
- all frames stacked, 21x 4 mins
I didn't quite manage to crop in precisely the same place - I haven't figured out how to do this yet - so that may skew the histograms slightly. But there's ever so slightly more background nebulosity in the all frames stack, with a little less blue overtone than the best 15. This was also cropped less than my original post, so it's going as close to the edges as I dare, to ensure the slight frame misalignment from stacking is chopped off.
Thoughts? Am I obsessing?