8" and an ED80 plus cameras would equal EQ6 as a bare minimum, personally I would up the ante to a G11. And in time I will be doing this myself.
Please keep in mind that if astrophotography is your aim then get the absolute biggest and beefiest mount that your money can buy - mount is king in respect of astrophotography.
I have an Heq5 pro, 8" newt (f5 so it's shorter than the standard newt that’s on a dob and weighs a bit less) and a short tube ED80. Once you add the DSLR and a web cam for guiding, it's definitely at its limits, if not a little past it.
For a start I've had to add more weight to it to balance it and that adds a bit more of a burden. I'm only starting out down this guiding business and have jet to get it to work properly and I suspect that weight is the biggest factor in me not being able to guide properly, weight and trying to figure out the right settings in PHD, but that's a whole other story. I had to add 3.75Kg on the weekend to balance it out
I have a feeling though, that i can get it to work ok, if I can get the balance perfect, but it will need to be PERFECT!!! I'm about the buy a cross bar so that I can mount the ED80 next to the newt instead of on top of it. That way the weight is not to far away from the mounts center of gravity, this should also mean I dont need as much counter weight and hopefully result in better tracking.
I will have to upgrade at some point so my advice to you is if your gonna get a mount get the Eq6, because eventually your going to want more aperture and the eq5 has no wiggle room. Buy something you can grow into and not out of.
