Same here. The conditions you would need a REALLY strong bucket for seem to be the exact conditions you would want a bucket that was SMALLER, not larger, than the factory bucket too. I have a 72" for the skid loader and tractor, which is the stock bucket size... for digging hard stuff I swap out for a 66" bucket. I wouldn't want to go wider at the same time as heavier duty.
Also not sure why you'd need/want to spend for hardox, my factory Kubota bucket with 4200 hours on it had a few welds but the wear stuff was still in-tact, you'd have to put a LOT of really hard work to wear out a stock well-built bucket with wear strips.