In reply to gruber:
I've been using them for about 10 years. I find they are great, like an extra pair of legs. They definitely help going uphill, reduce jarring on the kneees going down hill, and are a balance aid for river crossings and boulder hopping particularly if you are carrying a heavy pack. I use them less if I am not carrying a pack, but take them with me now for most long days in the hills, if only to help with a long grind up.
I don't find they slow me down, and when I'm moving fast, particularly on the flat I often just carry them.
The only times they are a nuisance is when scrambling (if I meet a long scrambling section I carry them on my day sack), and when going through thick vegetation like bracken, maquis or finbos, where they catch and get in the way.
However they are great in African countries for parting vegetation to check for snakes before you walk through, and I've used them in Spain for keeping farm dogs at bay.
PS As you are 99 I am not suprised that you take longer to walk routes now! Without them you probably wouldn't be walking at all?