Update, I took the plunge and got the JD X350. I'll probably get flamed for not going with the heaviest duty machine I could find, but this seems to be a good compromise for my needs. Didn't need something of a level a lawncare pro would use, but wanted something better than a box store model, this seems to fit the bill.
Actually both dealers I visited told me the X350 was by far their biggest seller.
Trouble is with the models you guys mentioned is that the smallest deck size available is 48", I specifically said in my original post I was looking for a 42. As it is, the X350 is a tight squeeze in a couple spots (old one had a 40" deck), no way no how gonna get anything wider in those places.
As I noted upthread, transmission failure is not something I've experienced with previous machines, including a couple of box store ones. While I definitely appreciate the info, I didn't see the cost vs benefit working in my favor (even if the heavier duty ones were available with 42" decks, which they weren't).
It was obviously a good machine in its day, and I did consider doing just that, trouble is, this one needs work
right now and I don't really have the time to deal with it in the middle of the summer. Come fall, I may still repair this one. At my age (75) I kinda wanted to buy my final mower, and not have to dick around with getting another one in a few years when the old one (or a new-to-me used one) finally went toes up. I figure if I take care of this, it should outlast me.
All in all, I'm pleased with the X350 so far. It's quiet enough so I don't need hearing protection when I use it (a first), gas consumption with the Kawasaki twin seems about the same as the B&S in the old Ariens (despite the new one being almost twice the HP). I love the way it handles...steering is very easy and smooth and it has a surprisingly tight turning circle...much tighter than the old one.
I don't especially like the separate choke lever, it's kind of awkward when starting it, and I've really got to find a way to defeat the reverse-mow lockout (there is a button you can push to over-ride it, but you need to mash it down or else it might not engage). I'd imagine it should be something as simple as bypassing the switch, just holding off for now so as to not potentially void the warranty. The seat switch got disconnected after about 15 minutes.