I like the energy that #4 brings, though it loses the serpentine line (the letter S). I'd like to see what #4 would look like with the colors switched in Organizing Systems. Also, will it work on a charcoal background?
I like that .#5 makes the serpentine line more noticeable. One thing I liked about my original logo (you can see it at
http://www.organizingsystems.com/images/organizing_systems_logo.html) was that it wasn't perfectly round, and the "O" looked like it had been written with a marker, plus the serpentine line allowed for one side to be red and one side grey.
I got some feedback from my partner and two colleagues. Both have concerns that the #3 emblem looks too much like the Pepsi logo. But I really like the emblem effect - like a light is shining on it.