Well, the deal's done. I got the Kubota
B3030.
First, thanks for all the advice. It was very helpful to hear how others would approach my situation. In the end, though, I had to stick to my budget and make a tough decision.
My
B3030 will come with the 60" loader, 60" belly mower, ballast box and R4's.
No cab this time, though -- maybe I'll trade it in for one a few years down the road. The snowblower, tiller, and other implements will have to wait for later

I'm hoping I'll be able to pull my old Ferguson 2-bottom plow with this tractor. I'll use it in the garden, and maybe to rough up the ground in the first stages of some lawn renovation (assuming I can get a tiller at some point).
Either this tractor didn't have the vibration issue, or I'm not sensitive enough to feel it. So it wasn't an issue in my case.
The dealer was excellent. His price was great, and I'm sure the service they offer will match. To close the deal, he agreed to weld a couple of chain hooks to the bucket and give me the supplies for the first service. He even gave us free Kubota hats and toy tractors for each of my 3 kids.
Tractor should be delivered sometime later this week!