Performance-wise ? Not really ... ATM, they all use the ATI reference design, so outside of some minor differences (capacitor choice, memory choice, etc.), they'll perform the same.
The main differences between the brands is in the bundle packages and warranties. As I pointed out earlier in the thread, the HIS unit comes w/ Valve's Black Box when you buy it from NCIX (PM w/ directcanada.com to save $15), plus a pretty decent bundle in the box, too.