I have a Leki carbon pole which I used in the Grindleford Gallop and
found to be excellent.  However after 21 miles my right knee was aching
and I posted in here.  Someone mentioned Pacerpoles which I will be
getting for the next GG.  I have also just re-joined the LDWA and hope
to get some additional walking in before then.

I contacted Pacerpole with some questions.  I thought you might like to
see their replies, which I post with their blessing.  They also
mentioned that they heard that a group of Pacerpolers had won the Race
to the North Pole by two days (out of five teams competing) which they
mused were helped by effective arm leverage without wasted effort.

I found a link for that, look down to July 09
  http://www.aarnpacks.com/news/index.html

- On weight difference between the standard alloys and the carbons...

"Now there is a 150gm difference between a pair of Alloys and a pair of
Carbons. The Alloys though do extend longer so if you have a big frame
go for the Alloys; if a medium frame then either."

- On use of one pole and the way it concentrates forces on one knee...

"re the knees ..... when just using one arm+pole so that as the arm goes
from a bent to a straightened position (extension thrust) - the action
will also twist the body if it's not countered from a 'thrust' from the
opposite side. If only using one pole it should be of a height where the
elbow is a little straighter, so less extension thrust - whilst still
offering support and stability - working with its diagonally opposite
leg. i.e. using one pole (so three-quarteres of the body ....2 legs and
one arm) is really just making-up for a deficit for the diagonally
opposite leg (eg painful knee ....so the straighter diagonal arm action
is helping to off-load weight and help with stability). To maximise
performance it needs the whole body  (the four-quarters) to be  able to
enhance propulsion and stability - and better weight distribution
........as you move around our evolved vertical axis of motion for the
bipedal gait. So there-you-go!

You're probably in the habit of reaching forward a bit with the right
arm ....so you'll need to 'think Left ...left ....left ....' to begin
with, as the body looks for equality Left and right; you may need to
retrain - for some god habits.........which you'll keep for the rest of
your life....Walk-Tall........"

Hope that's useful.