On fencing-  We removed acres of 5 and 6 strand barb wire. What a joyous day
it was when that the last last "bloody" strand came off.  A wonderful
product that is not inexpensive is BAYCO.  It's a stretchy plastic-type line
that is very forgiving to horse stresses.  My babies, however, would easily
slip through  even 6 strands of. The babies are now trained from the
beginning in a paddock with 4 strands of Bayco and 2 strands of the white
electric poly/stainless.
Adult horses are easily maintained with 4 strands of Bayco and 1 inside Hot
strand  of the white poly/stainless. I have 1 paddock with only 3 strands of
Bayco- it's resident is  not the fence-meddler type.  I do not recommend
smooth wire even when it is electrified.  I know people who have used it
(hot or not) with success, however, I also know people who have horses with
sliced tendons.  I think...Cheese Slicer when I see smooth wire.   
I also have used plastic coated wire-  very difficult to work with and not
worth the effort.  I have a roll of Stud Rail that is still unused in my
barn.  It seems like a good, serviceable product.
For cheap and easy the best product I've found is electric tape.  My posts
are spaced  20ft. apart (I know a horse-farm that spaces their posts for
electric fencing at 30').  I used 4 strands of the 1/2" tape.  Only the top
2 strands are electrified.  In 6 mos. time I've had no problem from the 2yr
old colt and gelding  turned out in that small pasture.  I hired the labor
to have the postholes dug & helped set posts, nail insulators and string up
the tape.  
Although this particular "taped" pasture has no exposure to road or highway,
I do know some folks who have pasture along a very busy black-top highway
who also use 4 strands of tape.  They electrify all 4 and say they feel
quite secure with the solar fence-charger in control.