Has anyone else noticed this thread is almost a month old, and OP has never come back to check on it?
Anyways, just to add in on the discussion (because the M40 aren't talked about much) - I haven't heard the Logitech, but the M40 feel better put together than the Beats, but certainly weigh a lot (and you feel the weight when wearing them; the earcup design is kind of odd). The ANC is...less than impressive for $350. The QC15 are superior in terms of ANC and comfort imho, sound-wise I think there's some preference questions - the M40 have more up top (and are more forward up top; I think both are the result of the dual-driver), while the QC15 are smoother and bassier. For $50 less, unless the bass just kills the QC15 for you, I'd take the Bose. The Beats wouldn't be in the discussion imho - they leak quite a bit, don't feel well built, etc. The M40 aren't bad headphones though, and I've seen them go on sale for around $300 (which is not a bad price for them) - they can run without their ANC enabled (and they do provide passive isolation, keep that in mind), they include a lot of accessories, and they look cool; so that's worth considering too. I guess I'm just not a huge fan of their sound, at least for the price and given their sort of odd fit.