Eliminating your newly installed kexts one by one until you find the offender would be a good place to start. Loading them "correctly" would be my next choice. Neither this lan kext or the new audio kext for the dp35dp gives me a panic. If you don't believe me then try for yourself.
shouldn't be a problem. other extra kexts are properly loaded
I realise this is turning into your personal holy grail and if a panic on shutdown is the price you are prepared to pay then more power to you. The point is booting from an EFI partition and then re-installing a kext after an update just seems a bit easier than your bootloader approach.
what would be the point of having a separate bootloader if i still have to [touch] the retail leopard install?