It was installed over New Years, but people claim about two weeks with a 2500mAh battery (I'm using a 3000mAh battery, so maybe a few days extra). I'll report back once I've driven it a bit more.
I agree with the BKE light domes, they're definitely a lot more binary than the OEM 45g domes. I've got two HHKB's, one with about 2 months, and one with a few weeks, and I can already tell a slight difference. Here's to hoping they break in a little more. I know BKEs are very subjective, but I personally like the "cloppiness" of the domes. I've also got Infinity Gauntlets for hands, so I think it works better in my case.