I think you'd be amazed at how difficult it is to make a sturdy and stable EQ mount for a scope as large as a 12" Newtonian. When you are imaging you are magnifying any small vibrations 1000 fold. If you have plenty to spend, and you are really ultimately after a setup you can drive from your lounge room sitting at a PC, then get an SCT. I don't know much about them but a Celestron 9.25" I looked through not long ago impressed the hell out of me. And some of the the planetary imaging people are getting some great images with them.
You might consider grabbing an 8" Dob first to get you low-tech observing sooner. The cost will be insignificant compared with the imaging setup, which will take a while to implement. It's really diving into the deep end, but if you're that kind of person there is nothing wrong with that (... it's just that most people are not that kind of person
).