Looked at the first one, and that's in a game setting? And they test 600 ms??

edit: The second one is more useful IMO. It's hard to get under 100 ms with a roundtrip, but < 300 ms should be doable, right? So you do lose the sense that you are directly manipulating data. In most cases I think that's a good trade-off. Exceptions would be things like Google docs, but that's also because it's a well made app I trust to actually sync my data without loss. Unlike most SPAs..

300ms for network latency both ways, with server potentially doing its own network calls for data to fulfill the request, interpolating the html, and then browser rerendering client seems like a stretch