I'm faster climbing with them, using my upper body to help move momentum forward by pushing off...downhills i find no benefit unless its technical, then it gives you more points on contact with the ground. I always take'em!
I'm partial to the Black Diamond Zpoles.....my set come in a 9.5 ounces and they collapse down to 15.6 inches, so they easily fit in most packs. They can also be used to set up a tarp. They are one size and do not accept a snow basket, but otherwise money well spent. Having had 10 knee surgeries on one knee, I am now using these little guys religiously to take the strain off the knees while in the mountains.