I've tried this between hunting and 3D arrows, the latter being around 125 grains lighter. Both carbon.
If you shoot some kind of aiming method and you can memorize the gap difference in how your arrows fly, then it should be relatively easy to switch between. Otherwise, shooting instinctive out to 15-20 yards or so the adjustment is not that bad, but as Mark said above, you gotta put in the practice. This is especially true as you get out there to 25 and 30. 125 grains makes a huge difference for me at 30+ yards and I really prefer the small, fast arrows for 3D because that's where I take those longer shots.
-Paul