Word clock sync?

Anybody use the word clock or digital I/O for syncing the MPC to Protools(or other software) ect... and how well does it work? How hard is it to implement? Let me know what you think. I use midi clock right now and my MPC drops tracks into Protools at slightly fluctuating tempo rates. It is a hassle to fix this. I like to control Protools via MPCs transport controls rather than vice versa. I guess I should always track the MPC via Protools transport control in order to control the tempo of the track.
So what's best midi clock, word clock, or digital i/o sync

Also I would like use the transport controls on the Mpc to start and stop Protools, but have the Protools clock control the tempo so the the MPC tempo reads (EXT). Is this possible?

anybody?

Try Midi Time Code. Word clock is the master clock for all digital siginals and has little to do with midi timing.