One does not need to prop up with diesel. This really depends on the engine. Some don't make any more torque as diesels, and some rev just as high as glow on diesel.

The venturi for diesel will generally be quite a bit smaller at the same power output. I've seen as much as 50% less area is acceptable. For instance, an F2C team race diesel runs a venturi about 4.5mm diameter, yet makes around 1HP.