If money is not an option, then going with a hydraulic post hole digger is the way to go. You have more control, more pressure and you can reverse out of the hole. I've thought about it. I have a Universal Quick Attach on my backhoe that I could mount it to and power it with the same lines the power my grapple. It wouldn't be very difficult to make happen, I just hesitate at spending that much money when the 3 point one I have does the job.
Good luck,
Eddie
If a 3pt works in your area by all means go for it. They definitely are cheaper. In my case back in 2004 or so I bought a new 3pt digger and to this day it is still probably the most disappointed I have been in an implement purchase. Not because the quality of it or anything like that but because it simply wouldn't dig well in our hard ground. I ended up fabbing some weight on the top of it about 3-400 lbs and that helped a lot but made it so awkward to attach.