Everything you mention is what I read when I was on the "ACDs are SO expensive" bandwagon as well. Then some other posts that know, schooled me on the parts and pieces and why the price is so different.
And yes, the 20" is the troubled child of the bunch. It's the only one that's no HD and it uses an S-IPS panel. It's dimmer and when put next to either a 23" or 30" it's a bit harder to get matching colors, but that's due to the dimmer backlight. They are very color accurate however, and are the best 20" and value for S-IPS that I have seen.
For color accuracy and professional features. It's not for everyone, in fact I always try to sway people away from it unless their next meal is dependent on color accuracy. There is nothing wrong with a PVA or TN especially if you are going to watch movies and play games, the response time on those panels are better.
But for professional color accuracy, S-IPS and H-IPS are the way to go. Which is why color calibrating on them should be a breeze, anyone that is having trouble should take a step back and read the directions one more time.
That's probably the only thing I can see Apple adding to the specs. Give me HDMI which is the same signal as DVI with added audio in a much smaller port. That would also free up some space on the MBPs for another FW800 port or eSATA.... we hope Apple would do this though.
