i would definitely favour this dual tank option for off roading.. its peace of mind when you are offroading.. i heard that earlier models fuel tank is not big enough and range is very limited. also something to look out for is prior 2010 or 2011 model had some issue in front suspension, which needs to be reinforced to take the off road abuse.
on another note prado never had rear difflock. only center difflock, also some prado models have 150L fuel tank. so another plus point for prado.
if its me i will pic FJ over prado anyday. 😎