leafs is correct, obviously, but sometimes this is tough...
re: features, the sf wins hands-down. besides having a signal-processor loop, it has a tape monitor & balance control, which the 99 doesn't have.
re: sonics, i've never heard the sf, but everyone sez it's wery neutral - some critics say it's almost solid-state-like. i owned a rogue 99 magnum-version for about 6 weeks; it was wery tubey, w/no bass response in my system, possibly due to impedence problems. so, for me, i'd get the sf, even tho i've never heard it! ;~) but, as i'm way-happy w/my melos, i have no desire to look for something different.