Your dealer's prices on the snapper pro mowers are a little high (by a couple hundred compared to local dealers in my area).The s50xt is plenty of mower for 2 acres. At that price you should be getting the heavy duty commercial 19hp fx series Kawasaki engine. It also has zt3100 hydros, which are low end commercial. The s125xt does offer larger hydros and a larger deck, but a step down to the fs series Kawasaki engine. You don't really need the 61" deck unless you are looking at mowing a much larger property.
I mow twice what you are mowing with a 48" snapper pro s150xt and it takes me about 2 hours. The grasshopper is a good mower. It has separate pumps and wheel motors. This won't matter in your case, but the main thing I don't like about the 126 is fuel capacity. It only has a 3 gallon fuel tank. You would think for $6k you would get a larger fuel tank. I would offer $4500 for the s50xt and see if your dealer will budge a little. It is plenty of mower for your lawn.
The hustler raptor sd is another decent option. Not quite the drive train as the s50xt, but a pretty popular mower in the $4k range.