Excellent discussion. Are the Kilby's overkill??? You, bet; too the max (it's frickin' armour plate for Christ's sake)!!! Heck, the Kilby's have the ability to support the entire weight of the VX on a boulder centered underneath the VX and acting like a teder-toder without causing damage to critical drivetrain components.
As "VX-KAT" and "VXorado" beautifully illustrated the heat issue is non-related, and the total peace of mind of having your entire undercarriage protected front-to-back is absolutely priceless, especially if you are non-lifted at OEM stock height. Further, having the Kilby's on your VX greatly enhance the "re-sale value" of your VX and will easily up the asking sale price by about a grand (due to the have's & and the have not theory).
For example, the Kilby's are like having an option on a vehicle eventhough that option may never be used during the ownership of the vehicle.
Suppose the following:
A. VX with or without A/C. Yes; we know that A/C is a "standard option" on the VX, but if it wasn't then you'd still like to have it eventhough you may not ever use it.
B. VX with or without Bumper Winch. Yes; the VX never came with an OEM factory Bumper Winch option, but if it did then we'd still want it eventhough we may not ever use it. Heck, how many times have you seen vintage 4x4 trucks on the street that had a factory WARN Bumper Winch and the cable-coils are still perfectly aligned because the Bumper Winch had never been used during the entire lifetime of the truck???
C. VX with or without Kilby's. Yes; the VX never came with full belly-pan skidplates as an OEM factory option, but if it did then we'd still want it eventhough we may not ever use it.
Does the likelyhood exist that the Kilby's will never be used to their full potential during the lifetime of the VX??? Yes. However; by damned, like A/C and the Front Bumper Winch example above, I still want the Kilby's because it is available as an option to the VX!!! Let's say you see two(2) identical same-colored VX's with exact same mileage on a Dealership Sales lot that the only differance being is that one VX has the Kilby's and the other VX does not. Chances are great that you'll purchase the VX that had the Kilby's, rather than the VX that did not. 'Nuff said.