Six acres with a walk behind is too much. An older diesel 4x4 tractor and a 3pt brush mower is a better investment IMO. Bought mine new in 1990. Would not buy new now due to particulate mitigation on new ones.
Diesel sucks around here, granted they will run forever... if they decide to start when it is cold out. I would definitely get a gas one if I were to get a tractor.
I agree, the field is large for a walk-behind, but it doesn't need to be cut all at once. I only do it once a year. I just keep the brush out and avoid some pines and fruit trees I have planted for snow fence. The trouble is along the hedgerows, there trees lean over the field which I can no longer get under unless I cut them back. Plus I cannot fit the tractor down wooded trails or cut new ones.
I wonder if I can rent one to give it a try first, to see if it drops me dead or not.
