Jim,

Is there any reason I shouldn't use brads for trim that is going to
be installed around an interior door?
The trim is 5/8" at the outside edge. The drywall is 1/2".

I used 2" long 18 gauge brads (in my Porter Cable brad nailer) to attach
all the trim in our house. We have 5/8" thick cedar trim over 1/2" drywall,
and I spaced the brads about every 16". We've been in our house about a
year now with no problems whatsoever. All of the trim is very secure.

The brads leave much smaller holes in the trim than my 15 gauge nailer
does. They're practically invisible unless you specifically look for them.
If you plan to set the nails and fill with putty or something, the hole
size won't make any difference.

Anthony