We have considered many different engines...What it comes down too, is can you pick up this engine or any other.
Remember, they are heavy and act just a little bit different when running and in your hands. At least for me 500 or 600 lbs. of saw is all I really wanna handle...I have seen however V6 Bill work up a big "MAD" and lift his saw a half dozen times back to back to back etc. This is where the big boys play though.
Hopefully, V6 Bill or Birl (head wrench) will post pics of the newest unlimited saw on the circut as it is being built. And Bill, make this one lighter than you last saw......PLEASE