Guess it would depend on what you are going to do with the land next ?
First thing I need to know from customers:
what is your plan for the land?
If it's just pasture or food plots, mulch everything to grade or just under then throw down grass seed and go. Some of my customers that have done this put their cattle out 2 months after I finished my part. A few years back I did a small pine plantation job on 8' x 8' spacing. 5 acres of fresh cut small pine (8"-14" at cut) to be converted to food plots and maintainable ground was knocked out in a long day with my big machine.
If they plan to row crop, stumps need to be processed one way or another. Excavate, grind, root rake or blade them out. You can mulch them after removal, burn them off or direct burial. A lot of the decision comes down to stump size and efficiency. I've worked them most any way and burial would be my last resort. If burning, I would suggest digging a burn pit first to make the operation as clean and neat as possible. If the stumps are reasonably small, mulching them first, then root raking and a finish mulch pass could be fastest. You won't get it done with a skid steer mulcher, though. It takes hp to get that kind of work done in a timely manner. Stumps that are cut flush to grade will split out easier and often speed removal if you know the techniques.
If pine stumps have 2 years to soften, there will be much less work to get them processed. There are also soil tillers that could handle such a job with ease IF they have enough hp and sized according to the material to be processed. From what little I know about these, you will need to be close to 500 hp or larger to be efficient.