I also have a B15 that may need this treatment. I really like the 15. Mine however has the alligator cracking on top that I’ve never seen anything work on. One poster had good results grinding it off with a wire wheel brush and then refinishing the more open pore leather to some degree. Like the OP, the beauty is that nothing is lost by trying. I find the 15 more comfortable that the 17 which is possibly due to thinner leather that is sometimes mentioned. My experience with the 17s is hit or miss.