Not to bring back a (somewhat) old thread but I'm glad I saw this post. My '70 Duster has 10.95" '73-up discs and today my passenger-side caliper seized up on me; drove 8 minutes to the grocery store to pick up some things and when I got there I could smell burning brakes and smoke was coming from that wheel. I tried to hit the caliper with random tools in my trunk in an attempt to free it up but once I got back to my neighborhood it was locked up so bad it was pulling the steering wheel to the right and there was so much smoke billowing out I had to leave it parked in the driveway to let it cool off.
I've been debating whether to go with Dr. Diff 11.75" brakes or the 13" Cobras but now it's time to make a decision, these brakes are done and that side specifically has always given me problems with dragging and such. Replaced the piston seal once which kinda helped but it was always still not quite right. I know I need more brakes from doing track days and I am on a somewhat tight budget so it seems to me from reading your post it's not worth the extra 30%+ in price to go with the Cobras for what I need. I think I have the 2.6" diam calipers currently too so going to fresh calipers with bigger pistons and bigger new rotors (likely slotted and drilled, not a ton of street miles I do anymore and these stock rotors have lasted 30k+ miles) with the braided stainless lines will be a nice improvement. I just wish there were more options for pads.