Barry, I'd recommend the Celestron VX for visual and planetary photography with your C8, as you've got a Nexstar you'd feel at home
and it's a lot lighter than the EQ6, although no doubts that the 6 would be more sturdy (the tripods are practically the same though).
Not sure how it'd fare with the 120 though...is it bigger/heavier than the C8?
Might as well scrub that thought, it's not much cheaper than the EQ6
