Having a ravine to work with so there is not so many cubic yards of dirt need to be moved, and that being a pretty new machine, it sounds better than what I envisioned.
I have not hired a dozer in a long time (we own ours) so I can't help you there.
Good luck and I know it is an exciting time for you. He having built numerous ponds and up to 20 acres sounds like he should be fine.
