I've shot both since 23 years now, never had a problem. I've found the folded slide models more balanced and pleasant to shoot. Concerning the cracks, remember the SOF P226 folded slide with 20 years of service and circa 1 million rounds through it before cracking due probably to poor maintenance. So i think US vs German durability is the same. I've seen more frame rail wear on the milled slide models ( under the rail ) probably due to the heavier slide.
Both are great gun you can't go wrong with both.
Strange i've found i'm more accurate with the first DA shot with the old hammerspring design of the old Sigs.