If there is one golden rule in amateur astronomy and that is "Bigger is better"
Not really but you get the drift. If you are going to try your hand at imaging then consider this bit of maths.
Take the carrying capacity of the EQ6 and divide by two (50%). From that subtract the weight of your 8" newt, a guidescope, a camera, finderscope, telrad, attachment for camera to scope and all the other bits and pieces that end up being on your scope/mount. Now how much do you have left out of the original 50% You won't have much if any.
Now do the same exercise with the HEQ5. Which has the greatest left over or the smallest deficit? That's the one to get. I'm betting it'll be the EQ6.
Oh and btw in one of your other threads I made mention about the weights of mounts. It's not so much the weight as the awkwardness of it. My G11 mount without scope but including weights is around 45 ish kg. Take the weights of and its only about 30 kg. In itself not really that heavy. but boy it is awkward to move. But you work it out. Once you learn the best place to pick it up from it'll be fine. Oh and don't have your legs fully extended (if they are) you don't need them extended that far if your imaging and having them shorter (fully retracted is best) adss to the stability.
Sorry rambling on there. The long and the short of all that is, Keep the EQ6