Havent found the need for one on my 696 yet - and its been ragged round Brands doing 56's without a headshake in std road trim, also stable on the road on rideouts regularly with 9**'s & 1098's
Had one on my M1000sie - now that DID need it on hard acceleration, also had one on the racebike M800's this year - only needed for one racetrack tho (Mallory) where a combination of bumpy track & acceleration made the head shake
not required for the other tracks - even Brands where Clint was putting in 51's
C