Thus for many photos its not a big issue unless your prints are very large or you are cropping a lot. If you don't view or print at large sizes and don't crop much, you might have the same issue and not realize it.
That is always possible. I print up to 13x19 (using my Pixma pro9000 that I bought with my new 40D as a package) and of course I do crop sometimes -- but it is hard to claim I do it often and repeatedly -- so I could be missing the cases where it is "off" because I wasn't cropping, enlarging, or shooting at f1.4. Not sure. Heck, it might be because I'm at 10.1 mp resolution instead of your 18 mp -- but I haven't had a case where I've said "Huh. That shot looks soft - wonder what happened". Maybe I am just lucky in one of those ways