This might be a moot point if you can't equipment or don't have enough operators. The second crew I hired for my 1 acre pond had a D6 for grading and only moved dirt with 240 sized excavator and 25 ton rock truck. He explained to me that he can move 2-3 times as much marterial loading and hauling versus pushing it with a dozer.

He didn't have to go far (250 feet one way) but made crazy fast work with the big rock truck. Not to mention if you get into a different material, you might want to separate and spread elsewhere.