Airfoilmod, yes you are correct about fuel heating, the temperature issue was addressed in the AAIB report however there is a need for fuel heating if and when the FOHE becomes blocked. An earlier suggestion in the thread drew attention to a similar problem on the DC8 that was solved by reversing the flow of oil to have the hottest oil near the inlet face.
It might be a useful addition to the OH panel to have a differential pressure light activated by sensors either side pf the FOHE, I quick cheap mod that would alert crews to a potential problem.
An alternative solution could be to have air/oilHE.