What happened to the days when we use to give tanks 5-10 seconds to generate plenty of threat so the dps never has to worry about pulling off the tank, instead of just charging in with them and being a douche?
That 5 seconds won't effect your dps enough to really care, the only ones who can avoid it and just run in are rogues and hunters (TotT / MD) but they should be near the top of the meters either way if your concerned that much.