Your mind is made up.  The owners manual answers the question you are
asking.  It tells you not to use the thing in 4WD on dry pavement.
Whither in 4WD or not your truck will slide off the road just as
easily  if she gets a bit sideways
at high speeds.  If one wheel hits a slick spot and breaks traction it
can cause a skid, if its patchy you hit another before recovered going
to fast and your in for a .wild ride.
But what do I know, Everything I drove in the service for 8 years was
all wheel drive, almost 5 of them in Germany where black ice is a
normal state of being in the winter.  I've owned a Jeep J-20 3/4 ton
pickup, 4WD, a couple of CJ-7s, Chevy 1/2 short bed step side 4X4, and
S-10 Blazer 4X4 as well as one of its predecessors, a 4X4 LUV truck.
I was raised in the Adirondacks of NY.   If the roads are slick the
only solution is to slow down.  4X4 will get you through when the snow
is a bit deep, but it has nothing to do with how well your vehicle
will stay on the road.  The fancy scientific mumbo jumbo is about the
rules of  Resistive Force of Friction and the Coefficient of Friction,
nether of which give a dang about how many wheels are powered when it
comes to staying on the road.  Your truck being better in 4WD is all
in your mind.  That is not to say that is a bad thing.  Psyching ones
self up, or someone else out is all in the mind.   The danger is when
one over estimates one's abilities based on false assumptions, sadly
assumptions fortified by some very bad advertising by all manufactures
of AWD and 4WD vehicles.
Watch a rally race on TV sometime, you will see that the Subaru's,
which are AWD are just as prone as the FWD and RWD vehicles to ending
up in a ditch.  I usually root for the Subarus, why cant Chevy build
something like that Impreza WRX STI.

Whitelightning

That is the DUMBEST statement I have seen in a while - "True, but just
driving and not actually stopping, surely driving in 4WD has to add some
added general traction than driving in 2." How do you plan on stopping?
How about if a deer or a person happens to wander out in front of you?

4X4 DOES NOT give you better stopping power on slick roads. Oh and WL is
wrong on one account, it takes LONGER to stop a 4X4 on slick roads
because of the way the ABS is programmed to work when in 4X4. It WILL
make you one of those people who complains that "But officer I had it in
4wheel drive, why did I go off the road and get stuck 75 feet off the
road" or more likely the one we will get to hear about on the news as
"Another death involving an SUV".
If you are so deathly afraid of driving at night in the winter DON'T
DRIVE, and if you are driving at 60mph on slick roads you are STUPID AS
HELL, you are a hazard being on the road. If you already know they don't
maintain the roads very well SLOW DOWN.

Oh and to answer the last question YES it is damaging to drive the
vehicle at ANY speed on a high traction surface. It destroys the front
differential and the transfer case through a process called torque wrap.
99% of current 4 wheel drives use slightly different gear ratios from
the front to the rear, on a surface with low friction (snow,sand,loose
gravel, wet grass) this isn't a problem since the lack of traction
allows the parts to slip a little and unwrap. On a high traction surface
it doesn't allow this to happen. The amount of friction caused by the
torque wrap increase as the forward speed of the vehicle increases. Just
a fact. if you look in the owners manual it will even tell you NOT to
use 4 wheel drive over about 40 because of the added problems it can
cause.

Here is the routine scenario I get to see as a firefighter/EMT.
Vehicle being driven by someone who does NOT understand how to use 4
wheel drive properly. They decide to keep it engaged "just in case".
They then hit a small patch of ice with the vehicle and start to slide a
bit. They do the correct thing and steer into the skid. Front tires and
pull them around as they regain traction, which slingshots the rear end
around and they lose control and end up in the ditch on the opposite
side of the road facing the other way. This is when they are lucky.
Unlucky ones still steer into the skid, but the rear tires grab traction
first and this shoves them forward until the front end gets traction and
the do a nice pirouette onto the roof at high speed. Usual resulting in
the roof crushing down on them and if they are lucky they die then, if
they are unlucky they get to feel their legs break, spine break and get
to find out how fun it is to bleed out internally while laying upside
down in the ditch.

Steve W.