We got a guy local that snapped a shaft on his 14 in his jeep, running 42" IROKS. A weak engine, Dana 300 tranny, you know, kinda run of the mill stuff. Super clean break, the shaft was either a bad shaft, or was just work out.
The biggest weakness of a 14 bolt strength wise, is they are used, and how were they used before you got it? The 14 that WAS in my truck, was in a 3/4 ton that had about 60k original miles. When I put it in, I had to rebuild most of the axle. It had been abused. They used the truck like a dump truck... The one I've got in there now, sat with water in the housing. Again, had to be re-worked, but what is wrong that I CAN'T see.