Tons of documentation. Current thinking is HTC took the specs from the heavily armored Wurger, but didn't actually model the benefits from the armor (it had among other things more pilot armor, ammo armor, oil ring armor -- in-game we get PWs and oil hits every time).
It's been covered many times, and I only hope HTC has put it on the back burner to fix "eventually" rather than just ignore all the data. You go back to 2000/2001 when the A8 was introduced in AH1 and they're even discussing this extra weight but no added benefit from the armor here on the forums. At least, they're debating it, because back then they did not have the E6B nor the weight readout on it to help test and diagnose certain things.
It's about 250 lbs too heavy. (empty weight)