I tried the 634 on a whim after finding 888s weren't really to my liking and fell in love. I picked these up at Self Edge a month ago and have been wearing them daily. Just did my first wash yesterday after they started smelling a bit funky and I'm super happy with how they're softening up and how the seat is fading.
Also so impressive how much give this denim has. These were literally painted on when I first got them and now I can comfortably pinch an inch of fabric along most of the leg.