After a lot of reading and encountering the same
comments on static discharge - pro and con - as
you have, I went with 4" DWV and haven't noticed
any static at all.
My environment is hot and humid most of of the
year though, which may account for it.
To second the comments already posted, a chip
collector is wonderful since it keeps the nasties out
of the fan and bags. I ran across plans somewhere
for a labyrinthine box with inlet and outlet high on
the sides. It's a simple ply box with a vertical divider
coming down from the top. I caulked
the seams and added a short piece of 4" PVC on
the bottom for emptying with a cap just stuck on it.
It's hung on the wall with french cleats in an adjacent
room next to the DC. About an inch a year of sawdust
and dirt makes it to the bag.
Only thing I'd change is to hang it higher so it would
be easier to empty.
I use 2 45s instead of long-sweep 90s since they
were cheaper at the time and provide as big a
curve as you want.
-J