I use FD-UR #3 all the time. I have not had any issue with breaking and some I think would be a couple of years old. They get mixed in with new ones I have bought. Pete sent me some he got from Garnet Hall that he did not like. I tested on my EX-21 and then have used with my 101 coursed on DW788. Not a problem.
Recently the blades were slipping out from the bottom blade holder.
I did everything I could think of changed to pegas, removed bottom blade clamp and screw, reset, sanded the blades, degreased - still no change.
I have an EX-21 and checked the arm was parallel to the table and it was out just a hair. reset and there has not been an issue since.
Back to my favorite blade FD-UR.