Oh my, a stabilized bigma eh?
That doesn't interest me anymore, I think. ; I used to be very interested in it, even without stabilization.. but I admit it, I'm a pixel peeper, and for the money I don't think 400mm gets any sharper than it does on my 400mm F5.6. ; The bigma might be able to outresolve me at 500 if you stopped it way down, probably beyond F8, but at that point you're sacrificing so much light at the time when you need it the most. ; Nah.. even with stabilization I think I'm happy right where I am.
As always, if this puts more pressure on Canon to drop prices or improve the lineup I certainly won't complain, but.. ; well, I'll still be very interested to see how the stabilized bigma performs in terms of image quality. ; If it can beat the Canon 100-400 for similar price it'll still be a very interesting lens.