The PowerColor Adapter is technically better than Sapphire's, because PowerColor's can go up to billions of colors (32-bits), where as Sapphire's only goes up to millions of colors (24-bits at 8-bits per component).
But that doesn't really matter, because what's mainly used is 24-bits. So either one is fine.
Both the 24-bit and the 32-bit have the same amount of colors in this context. They are both 8-bit per RGB and don't have bandwidth for more on a 1080P image. :) For higher color depth, specs indicates dual-link DVI/HDMI or DP. Only those have bandwidth enough.
I also don't think either of them produces DP adapters, so chances are that both are an Acell adapter or similar created within the specs of Eyefinity and slapped a sticker on by Sapphire, HIS and Powercolor.
In any case, reports indicates that those Eyefinity adapters were just what the doctor ordered! :cheers