The John Deere website definitely shows the "turning radius" as 25" for the X700 series and 7.4' for the 1026R (pull up either model and check under Steering Specifications). The website also shows that the X740, for example, is capable of a 28" uncut circle radius with the 62X deck. However, I can find no official reference to the uncut circle radius for any deck on the 1026R.
The Husqvarna seems to have a much wider turning radius than I would have expected, but it does work. Inexplicably, the turning radius to the right is almost twice as wide as it is turning to the left. Turning right, I bet it's not far off the JD 1026R's 7.4'! Whatever it is, it's not possible to zip up and down adjacent rows without doing a 3 point turn at the end of each row. Instead, I've been mowing around the edges and zipping up one side of the yard, half way across the yard on the other end, and back down again. It's a rather inefficient way to mow, but its faster than the push mower by a long shot. It would probably take me about 2 hours to mow the whole 1.5 acres with the Husqvarna, vs. ~6 hours to do it with the push mower.
Now, if I could mow the whole place with an X700 in about an hour (pure speculation), it might save me 35 hours per year. Between that and the predicted satisfaction of driving a high end garden tractor, it's probably something I'll think about constantly until I finally buy one.
Update on the Husqvarna: The shop discovered a missing washer on one of the blade spindles. Once they added the required part, the noise problem was resolved. So, for now, I have a working mower that doesn't sound like a helicopter. The cut is pretty good, too. I can make do with it until it breaks again or until I can build a shed big enough to cover something larger.