I was cheaper than M earlier this year . . .
for the following itinerary:
DCA-JFK-PSA-JFK-DCA
I bought the tickets for this trip, which we took in mid-July, sometime around March 1. At the time, I, which is a non-refundable business class fare, priced at $2,500.00; M class, a coach fare upgradeable to J, which has a penalty of something like $200 to change, was pricing out at just above $2,700.
Not only did we save money with I, we were confirmed in J both ways immediately (and also in F on the DCA-JFK connection on a CRJ-900; the return connection was on a CRJ-100 with no F class).