Er...This is my first time here to ask and maybe this question is not so related to OnePass, but I'm just too curious about the difference between Y class and M or B.

I mean, take round-trip EWR-NRT for example as I checked on co.com, it's something like $4565 for a Y ticket but only $1150 for M, then whoever would buy a Y? Or this is the very reason why passenger w/ a non-Y ticket should pay nearly double miles plus an additional service fee to get upgraded?

I raised this question becuase I might start to fly between NYC and Taipei recently frequently (frequently I mean is merely twice a year, but the point is I might do this for the next four years or more...), and I am very interesting in CO's program. I am just not sure if CO's OnePass would be a good choice. Or is there any other suggestion? Thanks!!