I use at most one pole (except in winter) - I like to have one or more hands free for climbing up boulders, and also I just like to carry a minimum of gear.
The Approach, being a three-section pole, met my needs very well by being able to quickly collapse into a size short enough to stick into the webbing on my day pack with only a minor risk of getting caught on an low-hanging branch and no chance of spearing myself in the back of the leg.
Collapsing & extending the Approach were quick and easy. I frequently found myself adjusting the height to match the slope (eg, shorter when holding in my uphill hand), just because I could.
Though I have heard tales of flicklocks slipping under weight, I had no such problems. (Caveat: I weigh under 150 lbs) Rain, snow, cold, made no difference.
However, I once had a problem with the lower lock - a sort of spring-loaded peg that lines up with holes in the shaft and is disengaged by squeezing. It can be hard to see whether this is properly engaged, and any sort of contamination (eg, sand, ice) can prevent its proper function. Fortunately the joint is nearly sealed, so this only happened once.
But this spring, after only one year of use, the Approach failed me utterly. The lower lock refused to engage - apparently the spring had broken. (Naturally this happened suddenly on a rather icy trail.)
Summary: nifty idea, not robust enough to be worth the price.