I've gone through 4 warranty remans and each had lackluster braking, some scarier than others. The last one was the best with a lot of spongey feel and required a football field to stop it from 60. Then it too failed, and when the pedal on a dually hits the floor when you're approaching stopped traffic it feels like you're accelerating.
I bought a new one today, cost almost $80 instead of the $20 for one that has been re-re-re-re-remaned. Now the brakes feel solid.
My theory on the remans is they must hone out the bore everytime thus making the cylinder volume greater, a smaller bore master sends more hydraulic pressure to the slaves and calipers right? Then probably using the same plungers making the seals more prone to failure. Just a theory...