At first, it seems ridiculous. But then, losing all counterweights does save quite a bit of weight! It would also completely eliminate gyroscopic precession from the crankshaft (the reason why MotoGP bikes run their cranks in reverse), which would make for quicker handling and turn-in.
If the thing actually did not vibrate at all, that would be a weird sensation, no? You hear the rumble of your twin motor thumping, but feel nothing from your seat.