Stability and speed are both better with pfs and sfs vs ffs. Personally I'd never use ffs these days, but mostly due to the disk becoming invalidated easily when using that file system, especially if the system crashes while the drive is in use. Read speeds have improved with os3.x ffs at least due to using buffers, but apparently write speeds suffered from it. Maybe set up a "test" partition and use different file systems on it, and compare speed, etc. there vs. ffs so you can see for yourself what benefits the different file systems offer?
One thing that ffs does have over the others though is better hdd tools.
