Ross,
It appears to be the head having a design defect allowing the the pressure and thermal cycles to 'work' the head gasket until it fails adjacent to one of the cooling pass-throughs. The new heads are over half the cost of the job.
Gotcha, I would think Ford would have tried to exhaust cheaper methods than replace the heads, but I think back to 6.0 diesels. They would lift the heads with boost, but adding head studs would let them live even when asked to do crazy things. Though maybe you could cheat there and get off cheaper if ARP made a stud that would work
The 6.0 head gasket failures were mostly due to the EGR system, not boost. Stock head bolts are will hold to around 450 rwhp and 45lbs of boost if the tune is good.
Every manufacturer has problems, but overall Ford does pretty good as a company. Their warranty return rate is pretty low. I've had stuff from Ford that was crap and others that have been fine. My 2001 Ranger 4.0 SOHC now has 291k miles and it's had 2 EGR valves before that got turned off and a month ago I finally had to put new valve cover orings in it. Alternatively I had a Toyota truck that had to have the FRAME replaced under warranty because they break in half. For whatever reason, brand loyalty, media coverage, etc. you don't hear too much about the import failures than you do domestic.
It just sucks more when it's your thing that is the defective one! Been there and done that. But I'd buy another Toyota truck if I found one I liked even after my warranty frame replacement. A sample size of 1 that I've owned and failed is just that, 1. I could own a 100 more and maybe never see the problem again. (Ok, well with my luck 99 out of 100 would fail, but my bad luck aside you get the point).