It won't make a difference as knee pain is generally a function of seat height or cleat position.

I will be a voice of descent against the steep positon as I rode that way for five years and always had crotch or neck pain at anything more than a 40 kms distance despite two tri bikes and all the fitting available (FIST included). The big disadvantage of the steep position is that it puts more pressure on your crotch and forces you to hold your neck in more extension. Some people find this quite uncomfortable. I got rid of my tri bikes and now ride a Kestrel Talon at I'm guessing about 77 degrees max in the forward post position. For me at least a little bit slacker and a little higher in the front has translated into a lot more comfort and even slightly faster bike splits.

The people that are claiming to be riding at 84/85 degrees are incorrect. The typical tri bike has a fixed seatpost of 78 degrees. The saddle allows only a few cm of adjustment in either direction from center of the seat railing. This will not give then an extra 6 or 7 forward degrees. Do the geometry calculations if you can still remember high school math and you'll see.

They may claim to be riding that steep at the tip of their saddle but that is not an accurate way to measure seat angle, particularly since nobody rides on one saddle point position at all times. Under power there is a tendency a rider to pull the body forward on the aero bars such as you see on 20/40 kms TT's, hence the saddle tip riding. Roadies do the same when sprinting. Not many IM will sit comfortably on the saddle tip for 118 miles however.