Regarding the toe, I can tell you that you have it set up wrong. The only way it can come off is if it's at the top of the height adjustment, which could only happen if it's set up wrong or you are trying to use a non compatible boot like I e with a vibram sole for example. Regarding Fks I don't think you need them at your size. If you really want to switch look at the px12. They are actually easy to replace brakes on if you break a brake again and it uses the same toe as the
Fks140 and it will cost a lot less. but I would go with the new sth2 13.