minimum thickness is key here. Too thin = bad things about to happen.

FWIW, I've never had a problem changing out just pads onto used rotors, especially if the pads are the same compound as the previous ones. Different compounds can cause some issues that usually resolve themselves in about 500 miles or so of "normal" driving (mix of city/hwy).

If you can stomach the delta $, then getting another 40k miles trouble free would be preferred, of course. I do my own work and hate rework as much as JCL, but I just haven't had a problem. YMMV, of course, as my braking isn't considered 'typical' or 'normal'...

__________________
Kirk
Las Vegas
2016 X5 40e Mineral White/Black Dakota Leather, ZLL, ZCW, ZDA, ZDB, ZPP, multi contour seats, rear side window shades, HK stereo
2011 E90M3, 6-speed manual