To me, the residual isn't that important, sure a higher residual lowers your monthly payment, but it reduces any potential equity at lease end. With the M3 leases, you will probably have equity to sell the car outright at lease end and pocket a bunch of cash. A lower residual actually gives you more lease end options.
The money factor on the other hand is quite high for the M3 compared to the rest of the BMW lineup. About 5.88% equivalent on a loan. Still pretty reasonable and you can't do much better on financing with an outside bank or with BMW (unless BMW is running a special). Therefore, leasing makes perfect sense on an M3.