It's very true, all chammy are not created equal. My current fav is my team kits Champion System although I don't know if they are available retail. They have all kinds of valleys, hills, gulleys, and channels /img/vbsmilies/smilies/wink.gif
I also like my Perl Izumi Pro's, but I have not scrutinized the glory of the chammy, I just know they feel pretty good to ride in.
The chammy in my Mavic bib tights is also glorious. And where I have seen some questionable quality control in their wheelgoods, their clothing is some of the best I have ever seen. The detail is almost as good as Castelli was back in the 80's, with their lovely scorpion enamel inlays, etc. IMO these days Castelli still look good but the quality is pure junk.
My generic Perfomance brand shorts on the other hand have a miserably thin chamois, but what to expect for $30. These are reserved for my most desperate laundry days.
When I win the lottery I'll get back to you regarding Assos.