In reply to HeMa:
When I did the Nose last year it didn't have that much fixed gear, certainly not enough to consider bringing any less of your own. The Great Roof had some equalised nuts to lower out from at the start of the traverse, but none else. I spoke to a guy this year who ripped one of those nuts when he clipped it and fell ~15m. Changing Corners is bolt protected at its crux, so it wouldn't be hard to strip the rest of the pitch whilst lowering off if you fell. Someone this year also thought it would be funny to tie off some rubber ducks and slot them into some of the cracks on various pitches, with just the tat sticking out. I didn't hear of anyone falling for it, but my mate got one out.
I think fixed gear is a really interesting ethical debate. The Nose (and many other routes) wouldn't go free without the pin scars from aid climbers, but these pin scars can also often be filled with pins or heads, making free climbing impossible again. It was really interesting to see whilst climbing The Wall of Early Morning Light this year what Tommy Caldwell did to protect some of the pitches on the free Dawn Wall. I think he got tired of aid climbers cleaning and taking the beaks he placed for pro between his attempts at the wall. Given that he couldn't bolt an existing aid route, he chose to absolutely welly a few into the cracks on certain pitches with no cleaning loops, effectively permanently fixing them. They are in a corner and flush with the rock, so once the wire/thread breaks they will turn into useless lumps of metal clogging good placements for aid and free climbers. Not the most sustainable solution in my opinion. To be fair they might not have been him, but I can't think of who else would have done it.
I personally really dislike fixed gear on aid routes, as it takes away all the challenge and turns routes into sometimes scary clip ups.