"needs more adjustments/maintenance" is not the same as "needs more work to adjust"
I also disagree with that notion (respectfully).
My impression has been that Weltklangs are very straightforward horns. In my memory, having refurbed probably around 30 or so, I cannot remember them having taken more time to put into adjustment.
The mechanics are not unusual, the keys are not soft, the proportion of the rods to the key barrels not unusual, and they have no oddities such as Conn set screws or Buescher snap-ins, which make servicing them more time consuming, and they do not have a tendency to go out of regulation quickly.
Again, my experience with 'em....the only issues I found were in their very last ones....
(pssst - having never seen your *****, I would be remiss in casting aspersions upon it and offend anyone's tender sensibilities; so you can safely assume it wasn't the tertiary definition)
FWIW of the several Welt baritones I have serviced, I did not find them to have wonky intonation in the upper registers. I have had the pleasure of refurbing a pair of B&S Low A's, and they were IMHO Stellar horns.
I certainly did not notice anything dramatically off in the intonation; not with any of the usual range of tester mouthpieces I use.
Didn't particularly notice the neck taper....but I don't resell any horn I have worked on if I cannot get its intonation in the pocket.
But an interesting comment, nonetheless. I suppose if one were buying one and couldn't playtest it, they should clarify with seller the return policy (but that is the same advice I'd give for any second-hand sax transaction).