And conversely, the thing that today's houses have in their favor is that there's a ton more engineering knowledge and testing applied to the materials and cons

And conversely, the thing that today's houses have in their favor is that there's a ton more engineering knowledge and testing applied to the materials and construction. They will last a very long time, and they will do better at resisting leaks, staying level, and operating efficiently. Of course, at any time there are many poorly-built houses being made - it's not fair to compare only the old houses that have survived with the cheapest of current homes. And there are probably some "miracle materials" today that will be found to have big problems in practice, from lower-than-expected lifetimes to significant safety risks (c.f. polybutylene pipes, asbestos, lead paint). Personally I enjoy living in a 125yo home. It's balloon-framed, and the joist spacing is inconsistent, and if you replicated this structure with modern lumber it would probably be dangerous. With 1890s-era lumber, it's just a little off-kilter. :)