Let's look at the stats:
In 13 games in 2008:
Shipley: 89 rec., 1060 yards, 11 TDs
Cosby: 92 rec., 1123 yards, 10 TDs
Through 7 games this year:
Humphrey: 42 rec., 576 yards, 4 TDs
Johnson: 41 rec., 563 yards, 5 TDs
This year projected through 13 games:
Humphrey: 78 rec., 1070 yards, 7.5 TDs
Johnson: 76 rec., 1046 yards, 9.3 TDs
I don't disagree with anything you said about which guys are better at which aspects of the WR position, but it has to be acknowledged that this current duo is matching Jordan and Quan step for step in productivity, and they are doing so with average QB play, not having the benefit of a heisman finalist at QB throwing them the ball. And I'd say Humphrey is every bit as good of a route runner as the other two, and he is just as smart and just as good at finding soft spots in the zone. And you left off a huge advantage for the current pair in your comparison, and that is the ability to go up and make contested catches on deep balls in one-on-one situations. Collin doesn't just make short catches in traffic, he makes huge bomb catches in traffic.