Sorry Bob, I disagree...the 'speed' of a scope is not relevant for visual observing, besides being a factor of the focal length...a longer focal length 'slow' scope will have a maximum smaller true field of view with the same eyepiece than a shorter focal length 'fast' scope. The number of objects where this makes a significant difference is relatively small. What's most important for the fainter stuff is a darker sky.
Anyhow, what I'm saying here is irrelevant too because all the mass-produced 8" Dobs seem to be f/6
