Ted,
My situation was much the same as your's. I wanted to buy my LAST mower and I wanted to mow the 2.5 acres in less than 2 hrs. The previous owners took over 4 hrs with their year-old Yardman 48" deck.
With a bunch of commercial mowing from my younger years, and having used my share of crappy department store mowers, I started shopping and researching in earnest. I demo'd a Dixon diesel (Kodiak) and Walker Super Bee on somebody elses property. I demo'd a Grasshopper 722 and a Scag Turf Tiger on my own property. Before the demo's I was leaning toward the Grasshopper. The Dixon wheelbase was too short and bounced a lot, even when not running full out. The Walker's steering is unique and I imagine I could get used to it. It mowed beautifully, and for the money was probably the best deal given what I was considering. The Grasshopper was fantastic, as I expected. I really wanted the diesel, which the Grasshopper had. But, the Turf Tiger just blew me away! I was very impressed. Except for visions of a $12,000 machine sitting in the shop while I hired somebody to come grade our 1/4 mile lane...or clear the snow if we were to catch a storm or two over the winter, or tow a cart full of firewood to the house, etc...
I also mowed with the neighbor's old John Deere 455 and she did okay, but I wasn't crazy about the deck. Not entirely even and didn't cut well at higher speed. I'm sure the deck could be adjusted and I'm sure she would cut better if I had sharpened the blades. I was comparing her against new machines.
I really wanted the diesel. After weeks of deliberation I finally bit the bullet and bought John Deere X748 with the commercial grade 7-Iron 60" deck. WOW! I never demo'd one and now here it is sitting in my drive! It's 4WD, doesn't scuff the turf, turn's amazingly tight (especially considering it's not 4-wheel steer), climbs like a raped ape, and the deck is amazing! Beautiful cut. It comes on and off super easy. Just disconnect and drive over it. The front blade works better than I thought on the gravel lane, though the 48" box blade for the 3 point hitch is on it's way. It cost a fortune, but it's worth every penny.