Thanks for the heads-up!
Honestly, I hadn't planned on getting one. Using my gripped 5DII and 7D (with two LP-E6), I rarely got them below ~30% charge. On cycle one of my 1D X, I'm at 39% after 550 shots (and charging now), meaning ~1400 shots on a full charge.
But...what changed my mind isn't the battery, it's the LC-E4N charger. That thing is huge - I can't see taking it on a weekend trip, a second battery is a lot smaller.
So...ordered one from Norman via Amazon, since I have a few hundred $$ in gift card balance lying around.