My dad's B8200 handles a 9" auger just fine, and it's not much bigger. I don't think I've ever heard it even snort the engine, so I don't doubt it could handle a larger auger. Your question really depends on your soil type. If you want to spin a 24" or larger bit in heavy soil, you are probably out of luck. Large rocks and tree roots will be a pain on any auger on a farm tractor without downforce and a reverse direction on the PTO.
I don't know if you've used a tractor mounted auger before, so I'll give you my standard advise. Pack the wrenches to unfasten the auger mounting bolt and a large pipe wrench to unscrew the auger from the ground if it gets stuck on a root and corkscrews in. I'd also advise taking a manual post hole digger to make a small "starter" hole to allow the bit to start cleanly, otherwise it will tend to skip around a bit before it bites in. This will help keep your holes in a line. You also want to learn how much angle you need to have in the auger when you start digging, as the pivot action as the auger lowers tilts the auger as it goes down. They are a very nice tool to use, and you'll be used to it in no time. Best of luck!