One acre?  I've got you beat by a looong way!  I've got 1.03!  
 
When I moved in, the back third was forest.  I guess it was cleared when the house was built in the 70s, but nothing had been done since then.  The front was lawn with some big trees - sycamores, oaks, and cedar.
I've cleared the back except for a nice hickory, an oak, and three cedars.  some years later I took out 13 big trees in the front because they were in my septic field.  They ranged from a 10" cedar to 40+ inch sycamores.  I rented a 6" chipper for 3 days to take care of the branches from that project.
And now that's done.  I have the occasional branch falling, and that's it.
All that to say, you don't need a grapple 
or a chipper.  This is a one-shot deal for you and then your chipper and/or grapple will sit and gather rust.   Money 
not well spent.
Yes, I'm a party pooper.  
