The additional data helped to go a bit deeper, bring out more of not only M51 but some faint galaxies in the FOV as well. I will probably still go back and reprocess from scratch just to see if I can pull more out, but I am happy with it. I think I will move on to a new object now :-)
After culling the bad frames I had almost 5 hours of Luminance and just under
and hour and a half of RGB and that is enough for me for this object.
Same image, cropped onto M51: