I thought I'd post what I've ended up buying: after tossing up between the Audio Technicas and the Brainwavs, I ended up going for a pair of Focal Spirit Ones (http://www.amazon.com/Focal-529102-SPOH-Spirit-One-Headphones/dp/B007AH7YFU), based on a recommendation from my brother. While $400 here, total cost all-up from Amazon should be about $260 (depending on YouShop's shipping charges).
A decent amount over my initial budget, but hopefully worth it. It seems like the company had a significant quality control issue with (one component of) the model initially, but this has since been sorted (and the company clearly dealt with it well, going by stuff I've read). Given they come with a two-year warranty, I think it's worth the risk for a pair that deliver all the characteristics and features that I'm after. It will be interesting to compare them against my niece's Brainwavz, given they're at a cheaper price point.