Im considering the 42 inch Hustler Raptor, small 3/8 acre flat yard. They come with the Kohler 7000 Hd w/smart choke 22Hp, or the Kawasaki FR600 18 Hp. If taken care of are they both decant engines? Is one more preferred over the other? Will the Kawasaki 18 Hp be equivalent to the Kohler 22Hp?