Hi Col, imagine going from a FOA-60 to an FS-78 stopped down to 72mm. That is the kind of jump you will achieve. Image quality will be much worse in either dob though
Joking aside, if you don't have either at present and the 12 is no obstacle, get that. A 10" of the same design is somewhat (truss) or a lot (solid tube) easier to move around though.