Huge difference for me. My new Mizuno STx is almost a cheat code for me. Center shots go farther because I got the shaft fitted to me, so they launch higher and with much lower spin. But it is on off-center hits where the new driver really shines. Even if I hit it poorly, it gives me acceptable results. Because of that, I have more confidence and swing more freely, which also gibes me slightly better ball speeds.
It's a win-win and a positive reinforcement cycle. All the new drivers are fantastic, but I would highly recommend looking into the Mizuno offerings. Because they are not one of the 'big five,' their prices are more reasonable. Anything the TM or Titleist or Ping or Cobra or Callaway can do, the Mizuno can do, too.