Just wanted to say this is awesome (with pardon for the window manager related pun). I really missed this when I had to use Apple hardware a couple years ago.I know there are other solutions, but this seems really elegant, I'm just not sold on the way the floating bar works, because the area where you "drop" the window does not correlate 100% with the position its going to occupy. Maybe if it appeared closer to where you started draggin instead of the top of the screen? Either way, bravo.
PS: even though its nice to have instantaneous feedback. Often when you start arranging you don't really know how you'd like the windows do fit, its kind of a "try it until it feels good thing". This apparently does it really well.