Carlton, for planetary with your SCT, the 224 will be streets ahead of anything else. Only the 290 comes close. It’s just the most sensitive to date.
DSLR must be tricky up there with the noise, it’s bad enough down here for half the year
I ended up buying a cooled camera and it works well. There are plenty of options...
Best thing I can suggest is get to grips with your gear and get some images you’re happy with before splashing out on too many toys. Especially when it comes to the cameras, the technology is changing all the time and it doesn’t make sense to buy one you’re not ready to make full use of.