I have never, ever seen separated rod caps and pistons through the head due due to failed big-end bolts in a TDI. More like a subtle but noticeable squiggly bend along the length of the main rod column to something more dramatic like Andy's pic above but in any case, the bolts have not been the weak spot.
Edit: @Machineman, since you've already modeled both I- and H-beam rods in SolidWorks, you can easily query the software to report the moments of inertia Ix and iy of both designs. It would be very illuminating if you would post the results. And if your SolidWorks has the FEA module, you could do a quick and dirty stress analysis at different rod inclinations. I can give you some representative cylinder pressure vs. crank angle data for that analysis if you like.
