My buddy rides a Valk. The thing is crap at plowing and the lack of a PTO shaft makes it almost useless around the farm. A definite improvement.
Things so goddam heavy I'd think I he ever got a front tyre blow out the Valk would plough a substantial furrow!
P.S The write up on the opposing free piston turbine engined tractor is particularly interesting (to me anyway). High efficiency, no first or second degree vibration, run on almost any fuel surprised it never caught on. From what little I found out about free piston engines there were also linear alternator versions designed,neat concept.