The only one i can think of that has similar sound signature to Momentum is Senn HD650 (which is better, wider/bigger/more airy sounding). And that only if you don't mind with open cans and having higher impedance (which may require amp to make them sing). I would say momentum is being the HD650's small-closed version.
Well I need a closed can. The Denon D600 is similar, with just slightly more sub-bass (perhaps slightly too much since I LOVE the Momentum sound), but they're much too loose fitting so hinder movement and isolation somewhat.
Any idea how the Sony MDR-1R will compare?