I've got a small case W-11 payloader, it's just about the greatest thing off road. 4WD, articulated, and at only 11k lbs, it's portable.
The way front end loaders are rated is that the working size of the bucket is about half of the tipping weight.
The way these guys are designed is to have their rear ends come off the ground before the hydraulics can't life. They do this so that when they are loading dirt or rock, they get some weight on the front axle to get a bigger bite.
Depends on how big you want to go, but to have a working cap of 10k, you'd want about about a 3-4 yard machine. But a smaller machine can still lift 10k.
Only classification where I think forklifts win over payloaders is compactness. You also have much bigger tires on a payloader so more floatation.