WarmAndSCSI

Given the same peak power output, the twin turbo kit will probably put more overall strain on your lower end; mainly because it produces more of a punch down low. The more peak torque your engine produces, the more stress the connecting rods, rod bearings, etc. experience.

This may actually be exacerbated by the fact that a turbo setup will produce higher manifold air temps than an intercooled supercharger setup (assuming roughly equal compressor adiabatic efficiency). This added heat ends up putting more thermal stress on the piston crowns and other components, as well as increasing the chance for detonation.

In practice, I'm sure the difference between the two setups is negligible. Just don't trick yourself into thinking your engine owes you any sort of "reliability" once you force feed it. 11:1 CR + boost = ticking timebomb. Yes, good tuning offsets that fact to an extent, but the engine will almost certainly fail prematurely while boosted. You're taking an already high-strung, inherently imbalanced V6 and lowering its tolerance for detonation, pre-ignition, lubrication break-down, thermal break-down, etc. Not conducive at all to motor longevity.

Any claim to the limit of any OEM engine being good for a particular WHP or boost pressure range is conjecture at best.