When I buy a new lens (and over the last couple of years I've been through a few!) I also do the same thing, stick it on my camera, venture out & shoot away for an hour or so at all the various apertures etc etc, get back home & transfer all the shots to my Mac for viewing. I'm afraid I'm not one of those people who as soon as they get a lens do all sorts of lab condition tests to determine possible sharpness issues etc, as longs as the results look ok to me from my casual hours shoot then I'm a happy camper!
On my lunch hour today I ventured down to Guernsey's harbour area with my 20D & my newly aquired 24-105 f/4L lens. I shot away at everything & anything at all the usual settings. The lens feels great & a joy to use, very quick & silent AF/IS, extremely well built & feels very well balenced on the 20D. I've just finished viewing all the shots I took & I have to say that I'm extremely happy right now Nearly every image looks amazing quality, sharpness & clarity are the first things you notice, spot on all through the range. The colours produced look fantastic.
I sold my 24-70 to get this lens & having seen todays results I have no regrets whatsoever. I remember doing my 'hours test shoot' with the 24-70 when I first got it & I can't remember being as happy with that as I am now!
I'll try & post some of todays shots when I get chance. If you're pondering on whether or not to get the 24-105 then I say go for it, I'm pretty confident you won't regret it