I followed the reviews for the new thermarest quilts because I was thinking about getting one. Apparently, they didn't quite cut as much weight as they could have, but they aren't especially durable either. Additionally, the temperature ratings across the line are considered off by 5-10 degrees by most reviewers. You could argue that all bags feel this way and the thermarests are being unfairly judged, but with 700-fill down you could do a lot better at the price.
I would lean towards the Brooks-Range quilts (I assume you're talking about the Elephant's Foot?) because I have some Brooks-Range stuff and their quality is pretty good. Admittedly, if I was going to spend 300 on a quilt I'd probably look to the specialists at Katabatic or Feathered Friends first.