Marc,
Thank you for that info
BTW it looks like the reflections shown in the Horsehead shot appear because collimation is slightly out. With better collimation test images of Peacock tonight (mag 1.9 B2 star) showed only a faint reflection.
Rob,
The C11 will give you more flexibility with what cameras you can use because it has more backfocus (i.e you can use a DSLR) and perhaps its possible to use a filterwheel with a mono -CCD. It also obviously has a lot more light gathering power.
The C8 is better if you want to maximise field of view as well as keep costs down. You can still use 2" filters as there is an internal thread in the camera adapter for that purpose.
The sharpness is really quite superb and certainly better (per pixel) than the scope natively, or with a focal reducer.
Terry