Depending on your climate, a SCT may or may not be suitable. Down here in Sydney, I find that the corrector starts dewing around 85% humidity. So long as it stays around that it can be somewhat controlled with heaters, but at that point you're introducing additional local thermals that could affect your image quality.
I also have the Tempest fans fitted to my C11 Edge HD and they're great for equalising temperature gradients but have also found I need to watch the dew situation as they push so much air - and potentially moisture - thorough the tube, I've had it dew up on the inside a couple of times
I've just learned to use them sparingly. They are great though and don't introduce any discernible vibration into the image.
Take a look at the RC scopes such as
http://www.bintel.com.au/Telescopes/...oductview.aspx they cost less at least in the smaller sizes than SCTs and have no corrector to dew up. I'm very happy with my Edge HD scope, but I'm mostly into visual...
Also, I'm no DSLR expert, but for planetary you might be better off with one of the faster frame rate CCD cameras, but a 5D should be nice for DSO imaging and at f/8 the RC-8 should give you a wide choice of the fainter targets to work on
Just a suggestion, but an RC-8 on AZ-EQ6 might be an interesting place to start, but the mount is everything as the focal length increases...