I have been reading the hard sell on the Santana website about how their tandems have so many great engineering features; what's overbuilt and why, reasons for tubing and component selection. This sort of thing appeals to me. I can see how not as much engineering effort might have gone into one-off cruiser tandems from other companies. But Burley clearly made a lot tandems, there are probably just as many as Santanas in the sort of 20-yo range I'm shopping, and they all far outnumber Cannondale, KHS, Trek, and the rarer ones. I read some old threads here about their corporate doom, but not too much about the bikes themselves aside from "my FD won't shift" etc.
Are there any bad ones to watch out for? Any normal issues? Do they have any oddball features that would prevent maintenance or upgrades with currently available components?
What made them good bikes? Did they have any uniquely great features? Any significant upgrades I should hold out for? Santana for example has a timeline on their site showing when they went to 1-1/4 steerers, A-headsets, standard disk mounts, 160 spacing, etc.