I agree with Al. I have sold, (I was a Grace dealer) and personally owned many various F9 cartridges and have found that in most cases, the 47K setting is perfect. I currently have several F9E's and have tried many different phono stages with them.
I have owned a couple different phono stages that allowed the 100k setting, but I always went back to 47K. IMHO, the 47K setting is just fine.
If you are an ex Grace dealer then you should read Grace Catalog with recommended loading for F9 series where you can read than MANUFACTURER RECOMMENDATIONS is 100k Ohm, especially for those models with extended frequency range up to 60kHz. This is where 100k Ohm is mandatory. There are a few models in F9 range than have Shibata type and LineContact type of the stylus, those models are "F" and "U". Same situation with advanced series of the cartridges that curpassed F9 series in everything (those are F14 and LEVEL II series from the 80's with exotic cantilevers and advanced styli like MicroRidge).
Every Grace owner MUST try 100k Ohm recommended by the manufacturer, but the acceptable range is 47k - 100k.