Rough on a napkin math from the order configurator calculator. Setting aside Fed + Local tax incentives and Local sales tax for the moment (not likely to change the outcome).
Premium 4XE - $54,700
10% down - $5,470
10, 500 miles/year
Return after options term
36: $719.67/month, $25,980.12 total payments + $5,470 = $31,378.12 for 31,500 miles, $0.996/mile
48: 632.94/month, $30,381.12 total payments + $5,470 = $35,851.12 for 42,000 miles, $0.853/mile
Keep after options term
36: $719.67/month, $25,980.12 total payments + $5,470 = $31,378.12 (+ $25,100 balloon) = $56,488.12
48: 632.94/month, $30,381.12 total payments + $5,470 = $35,851.12 (+ $21,204.00 balloon) = $57,055.12
I see no real advantage to the 36 month term (I don't really have to have a new car every 3 years). you might want to run the calculation for your particular situation.
My plan is to go with the 48 months, drive it a LOT (probably 60K miles or more)... If Ford is willing to "forgive" the miles and give me an attractive offer on a mid cycle refresh of the MME at that time, I might bite. Otherwise, I'll finance the balloon payment with my credit union and keep the MME.