I mow 8 acres each week, and since it's been so wet this year, sometimes every four or five days. Unfortunately due to a progressively lame right arm I can't drive a zero turn. So I use a diesel X750 JD and it mows beautifully.
If I had more lawn, I would get a Swisher finishing mower and pull that behind me, with a combined swath that would sure cut mowing time.
I have not one but two hard to find Gravely wing mowers, 40 inch mowers that add to the 50 inch mow deck. One of my always want to do projects is to build a rig behind my Gravely that could run both wing mowers, a total of 130 inches, so figure a ten foot cut.
If I were you, and depending upon your budget, I would also look at commercial out front mowers made by JD and Kubota. And I'd sure look for a 72 inch mower if it will fit in all the places you need. Before I mowed 15 acres of lawn, I'd also add a wing mower to it. Yes, mowing lots of acreage gets old, particularly when the heat index hits 110.
You'd better have very few bumps and obstructions to get the acres per hour quoted by many. Few of us run our machinery at the max. I for one can't, can't handle the rougher ride.
I sometimes mow my fields with my LP finish mower, and it mows almost as well as my lawn mower; just leaves a little more residual grass when done. That seven foot mower sure does eat up the lawn, so if you can, go big.
But for just mowing, don't use a tractor; dedicated mowers are usually much better for a finished look.
