Mobile in-ear headphones with electronic sound canceling

So, since the announcement at CES, I've been thinking about picking up a set of Sennheiser's CXC 700 headphones once they release.

Sennheiser USA - Press Release - 1/6/2011

Thing is, the Sennheiser name has one hell of a price tag attached to it. I'm willing to invest even before reviews hit, because I know the company's pedigree. I'm just wondering if there are any alternatives out there that have a similar feature set. The adjustable sound cancelling is the major feature I need - I'd like to be able to hear around my music at work, but not when I'm on a cross country flight, or when I'm trying to get to sleep at home. I don't want to spend the cost of a quality Sennheiser unit just to try everything under the sun, so I'm turning to the community for experiences. I'd love to have great quality sound to come along in the package, but noise canceling is the most important piece of the puzzle.

 

I like the innovative 3 mode selection for ANC and ability to function without a battery but ANC phones have a lot of drawbacks like price, battery, SQ, weight & size. They mainly cancel out recurring noises which might not be suitable for daily use.

For $300 id rather buy some TF10's and get them reshelled into custom IEM's which can give superb isolation, fitment and SQ.

If you travel a lot then this might give you some peace.

 

Are you absolutely married to the idea of active noise cancelling (using electronic DSP + external microphones to provide noise cancelling)?

Passive noise cancelling headphones (in-ear-monitors) are cheaper, lighter, and provide better sound quality for the price you pay.

I am in a similar situation as you, where I want different levels of noise cancelling in different scenarios. So I simply went out and bought multiple pairs of headphones. I use Etymotic ER-4P IEM's when I want maximum sound quality and noise isolation (e.g. on airplanes). And I use an inexpensive pair of Sennheiser CX-300B's when I want to hear more around me, and want a pair of headphones that I don't mind getting beaten up (e.g. at the gym).