I picked up a NOS NIB F9e a few years ago and quickly replaced the stylus with the Soundsmith TOL, which I found superior to the decades-old, if unused, original. To my ears it needed to load at 100k for best results. Grace apparently thought the same; the included spec sheet had all measurements at 100k. I really liked it.
To my surprise, a year or so later I found NOS NIB F14 body on eBay from a Japanese seller. No stylus; they actually sold them this way. Using the same SS stylus, I preferred it to the F9, which I quickly sold. The F14 is more coherent, tonally realistic, and balanced top to bottom to my ears. There’s a winning rightness about it that holds its own against my much pricier MCs. The main differences from the F9, from what I’ve been able to glean, are a lower internal impedance—fewer windings or something—and improved wire. Loading at 47k is perfect. Still, the F9 is a terrific cart, and a great reminder of how good vintage MMs could be.