The only things FPS matters to me is:
1. Flight Simulation (is a rubbish to land a 747 with 8 FPS....)
2. Car racing games (is crappy go into braking zone with 8 FPS)
but... I always adjust for 22-24 FPS... If I get more I use it to add eye candy... everything more than 22 FPS is perfect for me
In outside view of SH4 I be also happy with 15....it looks still smooth...
Andreas