so I use the 1.4ex when I'm out shooting sports etc on my 70-200 2.8L IS, but is it worth throwing on for a long shot at a wedding? of skip the hassle? I know there is no right or wrong answer here, but was wondering if adding that piece of glass to my $1700 lenses degrades the quality of the captured image at all? I know it bumps the f-stop up to 4.0 as the new minimum, but other than that? pros or cons?