"At least some of them have an elipticle design which give them more fore and aft strength , but does that weaken side to side strength?
Are they heavier? I do not know?"
Recently I had to redeem an already expired gift voucher, so I purchased a pair of BD Contour Carbon. Only the top section is CF, they are elliptical.
I tested those against my BD Approach now about 7 to 9 years old . The new ones are lighter and stronger in every direction.
They also have a double flick lock, very easy to use and never failed on my Approach version.
Just in case, this is the way poles should be used.Note in particular the use of the strap.
http://www.alpkit.com/support/products/how-to-use-trekking-poles
Franco