I'm pretty much in the same shoes (except the part about money not being a problem!). I currently have a 3520 and a 425 to use on the lawn. BUT, I do not manage as much property as you will. It's not a question of enough horsepower with the 3520 or 3720 to meet your needs, they both have plenty. To me it's the physical size of the tractor you should be considering to cover all the tasks you will encounter with a 100 acre spread. The bigger the tractor frame the more stabaility you will find on hilly terrrain-pushing, pulling and doing loader work. And anyway, rule #1 in the tractor world, buy as big as you can afford!