Ok, now's the time. I am beginning the process to upgrade to what I hope is the first of second major purchases over the next five years in the hobby. This one will be a dob, and I'm looking for a truss design. I have a bad back, deteriorating disc at L5/S1 so weight is an issue. I know Ron Ford has Bill Cowles Coulter Dob for sale and I'll be sending him email to take a look at it, but is there any other recommendations (thoughts on Bill Cowles Dob)? Here is where I am leaning. I have a 10 inch so I think upgrading to a 12.5 won't give me much bang for my buck. So I'm thinking a 15 inch and I am willing to go used or new (probably prefer used). A used Starmaster or Teledit comes to mind. An Obsession 15 inch comes to mind but they do have a rep for the upper cage to be small causing in some scopes a vignetting issue. I have also thought of a used Discovery, I won't go new with them because of what is going on with that company lately or the Orion XXi14. The XXi14 I like because of the intelliscope feature, if I don't want to star hop I can simply input and go. So I would love input into these or other choices others may have: 15 inch Obsession 15 inch used Starmaster 15 inch Teeter (see Teeter Telescopes, they are back east) XXi14 Thougths? Thanks for the input ahead of time.