On the flex issue, are you holding the poles correctly? Look at the picture on this site.

http://www.personal.dundee.ac.uk/~pjclinch/poles2.htm#Features

The weight should be held entirely by the strap, in fact you should be able to open your hand while supporting all your weight. The only reason you really need grip the pole is to lift it up off the ground. If you grip the handle too tightly (as in trying to use it like a staff to hold your weight), it puts side loads on the poles which cause them to flex, not to mention your hand will get tired and sweaty. If you let your weight hang off the strap, all the weight goes straight down the poles with no flexing.

Also, I have found the rubber tips aren't very useful outdoors in most terrain. Maybe on dry asphalt or clean, dry rocks, but any water or dirt will cause them to slip. The carbide tips give much better traction on most trails, especially ones with wet rocks or sand covered rocks.