70-200 2.8 IS II vs. 85 1.2 II for Portraits?

DPReview007 wrote:

Guys,

I use the 70-200 IS II for people shots, and am considering adding the 85 1.2 II to my stable. The question is, would it give me any additional benefits over the 70-200 2.8 for shallow DoF photography? Yes, it is two stops wider. But would that blur beat the 70-200’s at 200mm at 2.8?

In terms of light gathering capability, it lets in about 2 stops more light, of which the sensor can probably capture about 1 to 1 1/3 of a stop (read the article F-Stop Blues by DxO.) To counter that, the zoom has excellent IS, which is good for at least 2 stops, so I could probably shoot the same scene at a lower ISO with the zoom. (I shoot lots of parties in low light.)

The zoom is obviously more versatile, and I already own it. If the 85 1.2 II was like $400, I would just buy it. But it is unfortunately $2,000, so that makes me do some research before pulling the trigger. I’m obviously also considering the 85 1.8.

Sadly, both the 85 1.8 and the 85 1.2 II is rumored to be replaces “soon” (whatever that means.) At that point, both lens’ value will come down (which is no big deal for the $350 lens, a much bigger deal for the $2,000 lens.)

Is there any comparison on the web somewhere?

Thanks guys!

...I did a model shoot a couple weeks back, and did the whole thing with the Sigma 70 / 2.8 macro despite owning the 50 / 1.2L and 100 / 2.  My point is that a 70-200 / 2.8 would work well (it's just huge compared to a prime).

However, if you wanted the extra stop or two, then I'd suggest giving the Sigma 85 / 1.4 a hard look over the 85 / 1.2L II (half the price and only 1/3 of a stop slower), or the 85 / 1.8 or 100 / 2.