i've got to say chris that is a really well done second attempt! wow, mine was nowhere near this quality. you are well on your way, i will say that the biggest improvement from here is taking FLATS. they are quite easy to take, i'd recommend 'twilight flats' after sunset slewing to an even coloured part of the sky, set your dslr to Av, mode and snap away as much as you can. apply those flats into DSS. just make sure you don't rotate the camera and there will be effective. after that just more data
I quickly made an artificial flat and subtracted it from your image, to get rid of the gradient - this method is no substitute for real flats.
Cheers
Russ