The MCU they use is from Silicon Labs C8051F330
http://www.silabs.com/public/documen.../C8051F33x.pdf. I spoke to Griffin about this same thing, but I wanted to see someone doing it first. I have found other suitible FETs replacements: ST Micro STD150NH02LT4 (Lower Resistance), On Semi NTD4804NT4G/NTD110N02RT4. There are other DPAK FET out there, but those are really cheap
. Let me know how it works out.