I bought both the cx300 and Bose Triportie models. I find the Senn's to be much better. The Bose have to be played at a louder volume and seem to need more amplification than the Senn's. Sounds is better with the Senn's although this may be due to better isolation. Bose does have a good bass range and do fit comfortably with the provided range of ear plugs but the Senn's are just as comfortable.
I plan to return the Bose unit and will soon compare the CX300s against the v-Moda Vibe's I just ordered today. I'm not sure if these two are in the same league but it will either be the Senn's or the v-Moda's which I keep.