(except in certain cases on OSX)
hello .o/ don't break my icons please :P
In my opinion, you should work with as large images as possible as contracting is easier than expanding. The kind of icons that look good small are pretty much the kind of icons that look good big, too.
I like f0rqu3's logo but it is a bit monochromatic, could do with some detail.
I think durand's is a touch too busy and I don't like the T (a pure image logo I think would be nice) but it is pretty and nicely symbolic.
Try cutting the diameter of the outer blue ring so it has approximately the same area as the red on the left.