The design of the cups can give the F1 a more open sound, but at the expense of any sense of impact for me. The sound is nowhere near as detailed as the SA5000, no.
If you're interested in the F1, the MA900 does everything it does and then some (though its build quality isn't as good IMO). It sounds very open and has a more balanced sound, with decent lower-end response. You could probably find it for the same price you'd find the F1, as people selling the F1 here would probably play up the "out of production--- collectible!" angle.
I prefer the SA5000 over the MA900 overall. While the soundstage may not be as open sounding, it has a better sense of presence. Voices for example make the hairs on the back of your neck stand on end at times because they sound like they're there in the room with you.
Edited by MuppetFace - 1/19/13 at 11:17pm