I swapped a disk fork into an old Peugeot so I could find out how well a disk would work in Seattle's rain. Braking was excellent, but the handling characteristics were pretty bad with the different fork.
if I were going to modify an existing frame for a disk, I'd add the mount to the rear triangle. It'd be easier to stiffen those tubes to handle the stress of the brake, and the dropout issue would be gone.
