Okay, I don't know if you've seen my other threads in regards to my stump bucket and grapple, but I'll tell you that they both work great with this tractor. Now, that being said, if you've got a bunch of really big stumps, rent a backhoe! See my thread "up to my neck in stumps".
I've dug down a good five foot with my stump bucket, and this one still doesn't want to budge. I've dug out a number of 6' long 16" diameter pine stumps with it, and I can pop out a 6" oak sapling with a stab or two.
With a grapple I can grab and move piles the size of a car.
But if you have a large amount of large stumps, and want them out quick, hire an excavator. The 40 or 50 series, aren't up to this chore.
Randy