I've found the Momentum to be inferior to the DT1350 by quite a margin... Their sound seems to be highly dependent on whether you can fit your ears within the cups (i.e. wear them around-ear as intended) or on-ear (as in my case) which makes them sound quite muddy and rather dark.
It's too bad you could not wear them around the ear. My Momentums fit perfectly, and even with the good fit I believe the DT1350s are better...but there is something about the Momentum sound that is addicting. The Sennheiser has less sub bass and more mid bass, but what it has of both is combined in perfect harmony. I don't want to use the typical Head-fi cliche and say that the Momentums are fun, yet I'm forced to do so in this case since that is exactly what they are - fun as hell. These two models complement each other perfectly. After all, a Headfier cannot live by bread alone.