What benefit/difference is there between a DOHC vs a SOHC? (besides the obvious 1 cam vs 2! )

 

DOHC allows you to do without rocker arms, which has some at least theoretical advantages (fewer moving parts, less mass to accelerate/decelerate so possibly quicker valve actuation). From a maintenance point of view, it's typically easier to adjust valves on an SOHC because you can have adjustment screws on the rocker arms, while a DOHC uses something along the lines of shims that have to be swapped out.

In practice, it doesn't make a vast difference IMHO. I recommend using however many camshafts came with the engine from the manufacturer.