D
Before I started with the Schwalbe Fat Frank's I had some Specialized LK's. (Low Knob!). I had a puncture after about 50 miles, and stuck em in the garage. A couple of years on, I put them on a bike I was messing with. Sure enough, a puncture on the first test ride.I did have a puncture with that tyre a couple of weeks ago. The tube had a pinhole in its outer side, but I couldn't find any sign of anything coming through the tyre. When I saw that nail, I thought, "Oh no, 1000 miles on the old tyres with no punctures and now two punctures in two weeks with puncture proof ones". I've done 1600 miles on these ones so far.
I wasn't under the impression that the Marathon + uses Kevlar any more. I think they were experimenting with just a rubber layer some years ago. I don't know where that took them but i'm fairly sure there is no Kevlar layer in there any more...or it goes to show that the Kevlar layer in schwalbe (and probably other makes) tyres IS worth having.
I'll admit I was sceptical at first, but after about 2500 puncture free miles I'm a convert.