I have some Schwalbe Ice Spiker’s, the wire bead version which are cheaper but heavier than the Pro’s. I think the Pro’s may also use carbide for the studs instead of the tungsten steel on mine?
I’ve not actually used them for off road as yet as I found my Trailrakers to be quite good at dealing with ice last year, probably due to the soft compound on the knobs.
I used them for commuting only, they are draggy in comparison to normal slicks as you would expect but I look at it as a positive as it’s extra exercise from my point of view.
They make one hell of a clatter on tarmac, I often left them on when the ice had thawed and more ice and snow was on the way, it’s like riding on 2 bowls of highly noisy rice krispies!
I’ve no idea how the tread would fare in off road mud as I haven’t tried it but the cheaper tyre knobs are a little ‘plasticy’ whereas the Pro version – folding bead look like a softer compound, but I’m not 100% on that, would have to check them out in a shop.
As for riding on ice, you could be forgiven at times for thinking it’s actually middle of summer, even breaking stopper power didn’t seem reduced that much. No exaggeration, they really do work on the blackest of ice, I’d even advise you to think about getting some of those stud devices that can be attached to you shoes as you may actually forget you are on ice when dismounting, the spikes work that well!
They are bloomin expensive though, I would suggest people wanting to dip their toes into the frozen water perhaps think about buying one for the front only, perhaps combined with a soft compound MTB tyre with well spread knobs on the rear, that might actually work well, then later you may decide to buy another for the full set, or not as they case may be.
Review of the pro’s here here..
http://www.bikemag.com/gear/accessories/Schwalbe_Ice_Spiker_Pro/