Good effort Doug. 2.5 hours should deliver a good result. A few comments;
- The image looks heavily sharpened/deconvoluted due to the dark ring around the bright stars. You've either pushed this too hard by mistake or it was intentional. If it was intentional i.e. you wanted to sharpen other aspects of the image, you should layer/mask the stars to keep the star aesthetics.
- As the others have mentioned the data is black clipped, so you've lost data in the fainter regions. The histogram shows two peaks which isn't normal. On closer inspection, it is the green and blue channels which are clipped. The red looks fine. This is the cause of the two peaked histogram. (See attachment below).
- Due to the RGB misalignment your colour balance is not correct, but weighted in the Red. On reflection, you've got close to the right tones for this target as there is still quite a lot of overlap between all three channels - presented in the blue box on the attachment.
I think some more time reprocessing this target would see a considerable improvement. You've got the data, so you should be able to stretch it rather hard without introducing considerable noise. I would suggest focusing on the 10x10min exposures in the first instance. Leave the 10x5min data for star colour management if needed or if there is an area of the nebulosity that is blown or washed out (white clipped). Even with the 10x10min data you can still manage the vast dynamic range of a target by stretching it at different intensities, then re-layering as required. Don't combine the 10x10 and 10x5 into a single image as this does not give you the best control in handling the range. Work methodically on a single set of data first.
Look forward to seeing more.
