Ok, I've had these for two-ish weeks (sorry, time to send em back!) and have used them mostly for listening at work. During this time I also received my HD600s and have been getting used to them. This should allow me to make some useful comparisons regarding open vs. closed and price range.
They seal out a useful amount of noise and I've found the comfort to be much less of a concern than when I first received them. I would echo what Electropop said above, that they definitely feel secure and this has its advantages. Still, I'd say after an hour it's time to take them off for a few minutes. I've also used them to listen to music at fairly high volumes with my SO next to me in a very quiet room with zero complaint.
I find their tonal balance to be even and pleasant but now that I have the HD600 I find the treble to be slightly rolled off in comparison - however, I'd much rather have slightly less treble than the same amount of treble but poorly executed. This also keeps them from being fatiguing. Though the presentation isn't as airy and natural (particularly in soundstage) as the HD600s they present a very satisfying amount of detail. I can trust them as a solid reference for checking mixes or simply listening to an album for the first time.
I always liked my Sennheiser HD 280 Pros. Unfortunately, for the duration of this loaner I had my pair loaned to a friend so I did not execute any substantial back to back comparisons. However, my conclusion remains: these are the best closed headphones I've heard. I've also listened to numerous Beyer models.
The bass on these is great. Listening to Clipping's "CLPPNG" album and the Night Slug Allstars complations and they bump.
I'm pleased that these are easily driven by an iPhone.
Forgive the scattered impressions but I'll simply say that I'm happy with the HD600 and my IEMs and the collapsible HD280s or the time being but if I see a good price on the FSP I'd strongly consider it. Just need to let my funds replenish. I'll probably feel stronger about this when I have a Geek Wave and will be listening to much higher quality on the go. They're versatile, sound good and look decent.
My suggestions to Focal for a revision:
-change the headband design so it doesn't look like an easy thing to break.
-make the ear cups rotatable so they can be made more compact for packing in a bag.
EDIT: Alright, I really am fond of them. I'm sitting in a public library lost in an album and they don't fatigue me like the HD280s do with their forward mids. Thumbs up. I'll need to get these in the next six months.
