Having the lightest weight engine is not always best, a engine with some mass also tends to dampen vibration better, all else being equal of course. I certainly would not give up my rossi engines and they are as beefy as they come.

The brodak control line engine you refer to is a special purpose engine, it's much less powerful than a similar BB R/C .40 and turns about 5000 fewer rpms than we are used to.