LisPro:
I have a 2305 and a 3720 Cab. I've had the 2305 for 3.5 years and have maybe 150hrs on it. I used to mow 5 acres (mostly flat) and now mow maybe 1.5-2 acres and use it for snow removal, FEL work, and mowing. I've also run a
chipper with it, used a 6' grader blade, and a 5' landscape rake. Both locations I mowed had a short but steep hill I'd mow partly sideways. I mow with the 62"mmm.
I can't compare stability to the X series but I can tell you the 2305 feels almost as stable as my old Craftsman GT5000 lawn tractor and with the ROPS it's definitely a lot safer. I would load the tires. Also, already mentioned is the 4WD. Without 4WD you only brake on a single axle and it's easy to 'slide' a 2wd tractor down a hill and slip sideways. Going straight up and down you'll never feel an issue with the 2305. If you turn on hills it's still pretty stable once you get used to it. The only time I've had it up on two wheels (or 1) was with the FEL and lot's of weight. Also, when I mow I leave the loader frame on (I take the bucket off) and I still don't have an issue.
Sounds like you won't be taking it into the woods but the 2305 doesn't have a lot of ground clearance. I've never broken my fan or filter but a few folks have when they are taking it deep.
It finish mows like you wouldn't believe. Myself when I mowed 5 acres, most of it was flat out in high range (around 9mph) and it was pretty stable (I'd hit the roof of my 3720 if I tried to mow at that speed).
Also the deck comes on and off in a second so if you do end up getting the FEL it's easy to get the deck off.
Load the tires and use common sense and I'm sure you'll be fine. Loading doesn't add much on the 2305 (probably 200lbs) but it does help a little.