Tom,
There is a review of 12" collapsible but not GoTo:
http://www.iceinspace.com.au/41-531-0-0-1-0.html
I have 12" Bintel solid tube Dob and I am very pleased with it. Before this one I had 8" Skywatcher Dob and very quickly learned that aperture rules.
Of course as others mentioned you have to consider other things like portability, size of your car, how heavy it is for you, collimation ect.
cheers
bob