Sigma 85mm f1.4 EX DG or Canon EF85mm f1.8 USM

Sigma or Canon,
which one would you prefer ?
the people who own Sigma will tell Sigma, on the other side, the people who owns a Canon will tell Canon. They both liked there lens, and they don't really miss something.
But how would you go for if you have to buy one them for your own.
While searching over the internet you will only find some laboratory tests.
From this tests you can only see both looks like, that they are very well lenses. At some tests the Canon looks a bit better, on some other Tests the Sigma gots better results.
But for which of them you will decide ?
on the one hand, there is the Sigma with an 2/3 more aperture of 1.4, on the other side there is this higher price of more then 500,-€ over the Canon.

So question is, is this aperture of 1.4 worthy to pay 500,-€ more ?
I tired to find an answer somewhere on the internet, but I didn't found.
I tired to search for a non laboratory comparison of this two lenses, but I didn't found.
but what i found where many comparison from the Sigma to the Canon EF85mm f1.2 L lens.
Ok I know that lens, and I know its great, but it coast 1200,-€ more over the Sigma.
Interesting where the results, the most people come to conclusion that the sigma as performance likewise as the Canon L.
But for me there are two points:

1. if you look at the prices the sigma is more close the the Canon 1.8 then to the 1.2 L
2. the comparison of this Canon 1.2 L and the Sigma where mostly done with an fullframe Body  

so what I will do know....

because I have to make a decision, I decided to test both lenes first.

so I can test them in the real wild, and also with my crop camera the Canon 40D. 

I will write my impressions and test results in some days.


Links:
http://darwinwiggett.wordpress.com/2011/04/12/sigma-85mm-f1-4-vs-canon-85mm-f1-2l-ii/
http://www.wlcastleman.com/equip/reviews/85mm/index.htm
http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Le ......