Very interesting method, relly never heard or use this kind.
In our case, ones engines became much more RPM ( I am sure you remember general theory from using torq and use RPM was all over the world) and it was implemented noise reduction rull 80 Db, if I remeber it right -it was earlier 80 then vibration became really big problem-it was extra generator of noise. So we put engines on rubber mounts then vibration start really killing everything-transmission rods, pipes. We tryed a lot of different ballnacing and nothing realy work. We still was able to make Km/h, but after every run we will need to fix something-those couple of years was really hell. Then some guy developed self balancing flywheel. It was look as follow-it has empty space in the walls-double walls around and it was filled with very small balls by 60 %. Ones flywheel is spinning balls destributed arround and make ballancing almost perfect, and the thing is there was no more problem with low or high RPM-flywheel was ballanced instantly by itself. Since that all problems got away. So everybody easy got 80 Db and speed got back.
Unfortunately we can't use this thing in the RC cars-flywheel is toooo heavy. I wish we can use it here, but weight will be unacceptible.