I'm having a hard time with your question, what is it? The larger tractor with more HP and weight will push a little bit harder allowing you to take slightly bigger bites. Do you want to be able to push over bigger trees? Do you want more brushhog capacity? Do you just want a new tractor? What is it that you can't so now that you expect to be able to do with the larger tractor?
Commercial type work requires commercial type equipment. You are ready for a dedicated grapple rake on the FEL. If after you pick up the grapple, you still want more tractor then you can make it work with the new tractor.