I went with the Sony MDR-EX32LPW's instead of the Sennheiser's in the end.
Two reasons:
- They were slightly cheaper (£14.75 on Amazon).
- They come with an ear-phone holder that you can use to safely store the earphone buds when not using it, and to wind the cable round when you're using it to change its length.
I must say I am very happy with them. One of my colleagues at work has a pair of CX300's, and both he and I feel that the base on the Sony earphones is much better, and the mid-range sounds are at least the same.
I can also confirm that (at least for me) I could pick up some noise when the CX300 cable brushed against my clothing, while the MDR-EX32LPW's does not have the same problem.
Of course the real proof is not the first impression, but the experience with continued use. I may post another update after I've used them for a while for anyone that's interested.