I’ve tried some of the different noise reduction routines (can’t remember if I did topaz) but I found that many of them over softened astro images because unless you get LOTS of exposure it detects them as being overly noisy.
You’ve captured a lot of fine details but it looks like the noise reduction has left everything very pastel (painting) like. Very nice image but I think the noise reduction is a little strong for my personal astro tastes