In reply to TobyA:
Don't think I've ever got any thing like 500 k & have found that it wears out quicker when the snow is very icy (maybe more common in the Alps/Pyrenees than Finland ?). Started using grip tape to avoid the mess that goes with klister, especially as klister as an aerosol spray seems to have disappeared from French shops.
Anyone, today I hired some skating skis plus boots, something I've been meaning to do for years & had a good, if short, day out (short as the weathers rapidly getting bad & my legs & lungs found trying to skate uphill hard work). Now thinking that I might even buy some skating gear as my old track skis are ancient and boots starting to fall apart (after 'only' 20 years !)