These - http://deckmatescrews.com/
I don't believe they are stainless. Not sure about the coating.
In my application I don't see screws being a problem, but I do see the point about screws breaking and nails bending.
I've had deck screw break on me as quickly as 2 years after installation. While I would use them on most exterior projects, but joist hangers is not one of them.
True, driving screws is easier, but for joist hangers use nails. If they go in hard to reach spots, use a nail gun.
Re: screws or nails. PT woods seems to turn into concrete a few months in the weather. I want to start this project now, but maybe only finish 1/2 of it before winter. I'm worried about dealing with rock-hard PT lumber when I resume next spring.