The problem with a three point mounted driver is you can't maximize the force of your driver. The three point not being ridgid allows the driver to give upon impact. Plus you are always looking over your shoulder trying to line it up on the post. I have never operated a driver mounted on a front-end loader.
Mine is front mounted on an old Allis-Chalmers D-15 tractor. It has a 4-speed transmission, with a 2-speed Hi-Lo shift. The 2-speed Hi-Lo clutch runs in oil. In the 25 years I've used the tractor to drive thousands of posts, I have never replaced a clutch.