Pat, I have owned two 82Z tenors and I sold them both for JKs. I kind of went round and round. I had a JK, sold it for an 82Z- went back to the JK - went back to the 82Z - went back to the JK. I'll spare you the details, but this cycle illustrates that, no matter what the benefits of the Yamaha, I just could never be satisfied with the sound of the Yamaha once I had the sound of the JK in my ear.
Regarding the ergos, I think that's a bum rap. You can get used to them. The Yamaha ergos are definitely friendly. I've had a Selmer III and those ergos were fantastic. But you know the funny thing? Every time I went back to a JK, the ergos felt like I was home again. IMO it's just a matter of getting used to it. I mean, it's hardly slowed Ernie Watts down, right?
I believe the QC on the JKs is quite good so the problem with the D is likely a matter of adjustment. OTOH, I'm not so sure that the price isn't a bit high, depending on its condition and age. And if it's several years old, then they did not pay today's prices for it when they acquired it.
There's a serial number/year of make someplace on the web that's not too hard to find. You might be able to get that horn's serial number, check the year of manufacture and use that as a bargaining chip to get the price lowered. Or, frankly, it it's in great condition and you find out that it's really not that old, the price might not be unreasonable. You'll just have to make that call.