Seeing how they spray it on all types of metal areas when insulating I would believe it to be fine.
It's not really any different than the original foam except it is denser and closed cell.
The two agents may be a little different but there is no reason to think it would harm the hull any more than the factory stuff will.
In fact I would believe that the factory foam would be worse as it holds water that would over time cause corrosion at the points where it is saturated.