Well, This is the dilemma i am in now after reading reviews of Momentum In-ear. SE 215 was my daily use IEM for commute/travel and at office until one fine day the connector jack started to dysfunction. I loved SE 215 for many aspects. The sound was never fatiguing, highs were smooth(that's how i like them), they were comfortable for longer listening, the isolation was great possibly the best when it comes to passive noise cancellation. They weren't a lot analytical though and while mid-bass was prominent, on certain tracks, they clearly lacked the kick/punch in the bass, never heard them truly kick-in when required. Cheaper headphones like Soundmagic E10 (which are certainly not bass head) had a lot of kick in the bass, sounded energetic on tracks like 'Runrig- The Stamping Ground', shures never had that impact.
Sennheiser has been a favourite brand of mine. What intrigued me about momentum in ear is the reviewers stating them having good bass extension and punch. This kind of sound is ideal for my need. Although i don't have the privilege to test them in person, i would like somebody to advise how they'd sound compared to SE215 and is it worth it for me to sacrifice the comfort of SE215 for the sound of momentum In- Ear because although SE215 never had impact in bass they never sounded to my ear light in Bass by any means.