Yep, that's another good example. Plumbing has always been an issue in the older houses I've been in mostly because it's next to impossible to change it.
Right, I do think you get diminishing returns once you get to "high end and well maintained early 20th or very late 19th century" buildings, a lot of these can accommodate more or less modern lifestyles quite well (albeit not all of them and they'd have to be renovated with stuff like adding elevators to 5-6 story buildings).
