A long time dealer and i had this similar discussion about the V-Rod engine. His opinion was that it doesn't have enough low end torque to be suited for a heavy bike.
If EPA standards continue to tighten,the air cooled engine as we know it is dead. If H-D were to re-engineer the V-Rod engine's bore/stroke dimensions and change the cam timing,it would probably make a great platform for the heavier touring bikes and trikes.