Open Bowl VS elevating scraper for 9inch topsoil removal on 100acres

Hi,

We are currently completing a job and the contracting company have asked us to take 9inches of topsoil off the entire 100-150 acre property as they are redeveloping it. We have been looking around and can hire either an open bowl or 623H elevating scraper (both self propelled, single engines I believe) and are unsure which one would be best. Any opinion would help!!!

Its for a farming property and they've requested it be about 9inches off the top. Because it will have cows on it not houses it doesn't need to be perfect but it does need to be quick and efficient as we are paying by the hour for hire. Also, it is only black/sand topsoil not clay but it has rained like twice here in the past 6months and the ground is extremely dry (our garden has turned to sand due to water restrictions). We were leaning towards the elevating scraper but are a little concerned the ground will be too hard for a cut. we don't want to use a dozer if we don't have to.

any tips on a scraper or how to go about the project in general would be really helpful.

thanks!
Aussie Chick