I just got my new 573s. The website said they ran true to size. They don't. Toes are jamming the end of the toe box. Looks like I'll be testing the (reportedly excellent) free return shipping process. The lady on the customer service hotline was very nice, and the process seems remarkably simple (apply the included return label, check the box that says "exchange").
The good news is that they were otherwise a perfect fit (width, heel cup, arch, etc.). Weighing in at 11.6 ounces each, they shave a full 16 ounces off each foot (my current boots weigh 28 ounces each)... I can only imagine how much lighter they feel 10 miles into a hike!
On edit: Website said they weigh 11.4 ounces. I believe that's for a standard 10-D size. Hard to believe the 10.54E I got would weigh just 0.2 ounces more. Would love to get the 11-4E under 12 ounces each!