CtL ta re the 'jawdroppers', very kind of you to say so. I wish I had the eloquence and ability to talk and write technically about this as well as you do.
HD which 'L' lenses are you using? I have two colleagues who have 20's and overall get very good results, without too much post processing. I know and it is well known that there have been problems with some of their 100-400IS/USM's, I understand there are several factories producing them and there doe's seem to be a few 'Monday morning, Friday afternoon' examples about. I don't know of a similar problem with other Canon 'L' and 'L' IS/USM lenses though. I must admit to not having 'done' the photo forums, having seen how pprune and another forum I'm a member of gets 'chaff' in the forums, its sometimes difficult to see the wood for the trees!
I know exactly what you mean and where you're coming from re the post processing, in the past having shot transparency 90% of the time. I must admit I'm nowhere near as far up the foodchain on photoshop as you are if you are using CS, and CtL's offer of playing with one of your images, may be a useful test. Perhaps if you have someone who can lend you a body to swap lens' on, do a set of test shots and see if there are significant differences.
My basic settings on my 1D are
jpeg quality all at 10 = highest
parameters = set1
colour matrix = 4adobe RGB
noise reduction off
iso expansion off
I have no idea if those will work on your 20, but if they're there it may be worth trying those, or some of them.
For info my post processing is done very quickly for forum/web page/thumbnail work in Google's Picassa. A free download with very basic 'control', it is surprisingly effective though, with a RAW converter built in!
rgds
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