The Sport is easier to operate. It uses the more familar YS pressurised tank system. It is a more user friendly engine and will run just fine on 20% nitro. It is less expensive and even though it is less powerfull than the DZ it is a crankcase-supercharged engine and still more powerfull than any equivalent 4-c in its size class.

The DZ 140 is being replaced by the 1.60. They are available end of this month in the USA. The DZ uses a pump with a normally vented tank. The head contains a fuel injector nozzle that is right next to the inlet valve. They tend to be fickle about starting and flooding unless you know excatly what you are doing and unless you have the right clamp on the fuel line at the right moment etc. They also need 30% fuel.

I would advise that you use the Sport version.