Probably easier on the forks than trying to jamb a big rock into a bucket.You would think the weight distribution of using forks might be hard on the forks but I guess that depends on what your forks are rates for huh? But I can definitely see that forks would do a good job of getting under the full width of a large rock compared to a bucket.
Weight is your friend when moving heavy stuff. If I have my BH on I can push heavier stuff than with some other attachment. Trying to do it with no counter weight is hopeless. I have 5,500 lbs powered forks so I can go wide and try to bring the CofG closer to the loader. I can't push a 2+ ton root ball/stump with a bucket because it wants to dig in and roll. With the forks I can usually curl it enough that the same root ball will slide on the ground. Remember to go slow and avoid turns (especially sharp turn) unless you want to be replacing your front ring and pinion gears.