Yes. As a matter of fact, that's one of the major reasons many of us do the conversions to begin with. Timing based on RPMs smooths out the running of the engine at ALL speeds as opposed to being locked into one set timing.

As far as the weight of the magneto helping balance the engine, let me expand on something mentioned above. The magneto is so big and bulky because magnets (used to trigger the spark) must be made of steel (obviously I guess). The excess aluminum is a necessary evil to balance out the weight of the steel magnet. In the end, the big magneto is just excess weight and real-world load that the engine is forced to deal with in order to run that brings nothing to the table for you, per se. That's why you see top-end RPM increases (among other technical reasons too) when electronic ignitions are used to replace magneto systems.

Lose it. Get an electronic ignition and be MUCH happier with your gas engine. (Flame suit on for this one) I really don't understand why anybody in this hobby would run a magneto system at all unless there simply wasn't a complete conversion for that particular engine. Some of the early Quadras come to mind. Unfortunately for me, I have one of them.