I haven't used FF since SF was introduced with PP11, but here's my sorta typical output settings for scenes with shiny and reflective surfaces or any OOT hair.

Scenes with plenty of lighting and minimum shadows I drop the pixel samples in half or more. If it's an indoor scene with tons of shadows I may even bump it another 200 or 400 samples because SF renders are so dirty.

I also typically just let the 970 render things, even though it's much slower than my 1070 I can still do other stuff with 0 slowdown with the 970 handling everything.