To be honest, I thought this thread should/could have been locked or removed a long time ago. It seems to be 85% personal attacks to and from Juan. Maybe Jerry Springer can step in and sort things out.
Juan, I have no horse in this race, so I will give my honest opinion.
I honestly think your testing methods are not sound. Without adding the insults that others have, I will state that you simply cannot snap a picture at 1/20; 70mm and expect to consistently produce anything but a blurred picture UNLESS you have used IS or some sort of stability aid, even with a perfectly functioning high end lens. However, I feel that the photography world should not be solely based on "test pics." It should, instead, be based on real world photos. At least that's my opinion. If you personally took all of the photos on your web site (from your signature), then you are obviously doing something correct because there are alot of good photos on there. Judging by your web site, you have alot of talent and a good eye, especially for someone in the beginnings of a career.
If I were you, I would simply NOT REPLY any further in this thread and maybe even PM a moderator (Suzy?) and ask for it to be locked so nobody else can post in it either. At this point, the dead horse has been beaten more than 100 times.
Good luck in your career. And, if you decide to purchase another 24-70L, I hope you get a good one so you can experience the best of this lens, it is a workhorse for many a fantastic photographer. The one you had was quite possibly just a lemon, unfortunately there are some out there. Not alot, but some. If instead you decide you need a lens with IS, try the 24-105L IS, it also is a superb lens that I personally can hand hold at 1/20 and 105mm And, since you use 1.6x crop cameras, the 17-55 IS is another great lens to consider. I used that when I had a 40D and I loved it. Again, good luck. Mark.