I thought I'd give my 550D one last chance as an Astro Cam. I was hoping that the cooler weather might reduce some of the noise that plagued me earlier.
This is the result.
8x5min, on M104 @ ISO 400. Scope SW ED80.
Still not happy with the amount of blotchiness in the final image, and if I shot at ISO 800, the noise is still quite bad.
But I'm happy enough with the final result.