I've owned both the MS1 and the FA004, and would agree about the FA004 being suited to more genres due to it being relatively neutral in comparison to the MS1, plus it has the wider soundstage. However, I have to disagree and would not say the FA004 is more comfortable.
I would purchase the MS1 over the FA004 unless I needed a closed headphone. The MS1 can be modded to suit your tastes such as increasing soundstage beyond that of FA004, increasing neutrality, or increasing bass, and other tweaks. Search for Grado mods: MS1000 (thread by nickchen), and SR60 mods (thread by Bilavideo), etc. Plus the MS1 is neater aesthetically, and likely better resale value.