As you said, paint is a film on the surface. Solid color stain soaks
in, for the most part.
Many house are sided with rough-sawn cedar - I still use paint. I've
done some that were in not-so-hot shape so I primed first. If the
siding has been well maintained I've gone straight to paint without any
problem. Occasionally there'll be a problem spot, where there's
peeling. But that's the case with anything painted. With scrapers
[putty knifes], coarse sandpaper, maybe a small wire brush, you can get
it taken care of. I would prime those spots to help prevent future
Basically I'm treating it as most any other siding. Some people want
the texture of rough-sawn to show through, but it'll show through paint
Solid stain just doesn't hold up well. My experience is that the
lifespan of the job is much less than that of paint. In order to make
sure the wood doesn't deteriorate, you have to stain it every 2-3
years. People don't like that.
To me, that's the main thing. The wood ends up drying out, shrinking,
curling up. Then the homeowner wants it to look right , so we're
re-nailing loose or curled boards -- then the caulk job starts. Lots of
caulk, which will end up cracking eventually, given the size of some
of the cracks. (I realize much of this little rant concerns homeowners
who don't maintain the home properly, but there are a lot of homeowners
The prep work before initial paint job may be a minor pain, but not as
painful as staining twice as often. And far less painful than
replacing a bunch of siding.