As soon as I looked at your image, the first word that came to mind was `clean'. I said `ooh, that's a nice *clean* image.' That's a great example of How It's Done. A CDK 17" OTA, a 16803 chip, and 11 hours of exposure time. That's how you get images of NGC 4565 that look like that! Great job.
I think you did a good job of denoising the background (although I'll bet you'd built yourself a very good SNR to begin with), and you sharpened the dust lanes by just the right amount, IMO.