We run shaft drive buggies and TC's, 6.5 BL in the buggies and down to a 12 turn so far in the TC's. Never noticed it at all in the buggies and it only occurs in the TC's on initial acceleration which we've learnt to adjust to.
Used to run rubber bands in TC's but had one snap adn it is was a pig to replace in time, never had a shaft break yet!