I've been using a pair of Leki Al/Ti poles for 5 years with nary a problem.

Keep the shafts clean and slipping won't be a problem.

For the price, go with the one's from REI.

If you use the Peter Clinch's "Scottish" method (for lack of a better term, since Pete is a Scot), you won't use the grip much of the time, as the straps carry most of the weight, keeping your hands from getting tired and allowing the weight of the pole to naturally swing forward.

Before "discovering" this method here on the forum, I grabbed the grip with my full hand as 99.9% of pole users do. After a few minutes with the Scottish method, it felt far more natural. I'll never go back to the full grip (except when technical pole tip placement is needed). Read everything you want to know about hiking poles, how to use them and take care of them on Pete's website: Pete's Pole Pages