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Just a few comments about Pauls points above.
First: While im sure there are some good sct's and bad dob mirrors around, the complexity of the sct optics means there are more optical surfaces to get right and theres more room for error. Modern dobs like the gso have very good mirrors and I have heard comments from a number of people that these dobs beat sct's in sharpness of focus.
Second: For object finding its much cheaper to retrofit a dob with dsc like an argonavis than to think one must spend the extra for a fork mounted sct just to find objects. Object tracking is another matter.
Third: The sct may break down into smaller pieces for transport, but is much more time consuming to set up and pack away. My 10 inch dob ota lays across my back seat, and the base goes into the boot. On arriving at a site i can be viewing within 5 minutes and pack up just as quickly.
Fourth: Coma is only an issue with short f-ratio newts and at wide fields of view that the sct wont allow anyway due to its slow f-ratio. Very few find a paracorr wanting at f5. Eyepiece abberrations are often incorrectly labelled as coma . It is true that faster scopes are more demanding on eyepieces and in general wide field eyepieces that work well at fast f ratios are more expensive.
Fifth: planetary viewing in a dob is not a problem with the right focal length eyepieces. Planetary imaging is another ball game.
THe point of my earlier post is just to point out that its not necessary to spend thousands of dollars to get good views, and that your not going to get superior views by spending that much more money to buy an sct.
Im not interested in astrophotography myself, but for somebody who is, an sct with tracking makes life easy.
Horses for courses.
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