| I am doing a test on this as we speak
| It has been going on for close to 2 years and I haven't seen anything
| unusual yet.
| This is sitting on the south side of my screen cage, out in the yard.
| http://gfretwell.com/ftp/PT%20lumber...2010-25-13.jpg

That looks interesting. Too bad you can't
sell it to Consumer Reports.

One comment: Personally I have found that
galvanized screws, equivalent to drywall screws,
can rust away. I don't think the problem is so
much the rust per se as the thinness of the
screws. They can't afford *any* rust. I wouldn't
use them at all for joist hangers because they
have little shear strength.

Similarly, I like to use coarse drywall screws for
light framing because they're easy to remove and
a lot less work than hammering. But I wouldn't use
them where strength is needed. They just don't
have anywhere near the shear strength of a 16d
nail.

The coated screws are heavier guage, though
they haven't been around long enough to know
how they hold up.

I don't have a nail gun. Sometimes I think I should
buy one, but there seem to be 3 sizes to cover
all nails. It's a lot of money and I'm always doing
different things, so it's hard to justify. (I might
frame for 1 day on a bath remodel and spend one
day doing trim, with 6 weeks of other work.)
But another hesitation for me with nail guns is that
they compress the wood as they go through. Time
and again I see where a nailgun was used to put in
twice the typical number of nails, yet they're not
holding well because they've essentially pre-drilled
a nail-size hole on their way in. On the other hand,
anyone used to using a nailgun would have a very
hard time accepting that criticism because the time
and effort they save is so substantial.