The Sigma is a much better lens than the Canon f/1.8, although it's more expensive (nearly double). But then the Canon f/1.2 is *more* than double the price of the Sigma. So it's a nice balance between price and performance.I enjoyed the read, and there were some lovely photos in there.
I'm hoping to pick up a 5D3 tomorrow, but will have to wait a while before I can afford any primes for it. The first will probably be the Sigma 85mm f/1.4, since I can't afford the Canon f/1.2.
Why don't you get the Canon 85mm f/1.8? It's an awesome lens.
There is an excellent review on The Digital Picture which compares all the 85mm models (including the Zeiss) which is worth checking out, although since I see you have the f/1.2 you don't need to because you already have the best.