I think I may have mislead in my first post and Island Tractor I agree that most folks will go the flail/bush hog route. Personally, I still feel I would prefer a medium to heavy duty flail with a "quick change" knife mounting system. For the price of a light duty flail mower and bush hog one can buy a nice tripple purpose unit for cutting, dethatching and clearing. You would benefit from one less implement to store/maintain and actually put to use an implement that will perform better across the entire spectrum from grass cutting to land clearing. A forestry flail really isn't needed... I think I posted this video before but here it is again in case anyone is interested. It's a non-forestry multipurpose flail that will quickly clear heavy brush at a efficiency and speed that no bush hog can match without severe wear and tear. After the area is cleared just switch to scoops or Y knives. Once most people have their land cleared there really is no need for a bush hog sitting around. These units fit many budgets from medium duty and up depending on how much land one has to mow and clear. Even "Value Leader" sells one for around $1500. Just not sure how it would last when put to task...
https://www.youtube.com/watch?v=2BG74dzP5S8