Here's another site with independently done tests. In this table the recievers are ranked by narrow spaced dynamic range. "Narrow spaced" being 2 kHz. These are not rankings of ARRL test figures like the Elecraft page are but instead are an independent series test done over many years.http://www.sherweng.com/table.html
There are some other white papers accessable from the home of this site as well. Good stuff.