In my opinion, as such things typically go, it depends on the scope of your tuple usage: I think tuples are perfectly readable/maintainable when used within the context of a single class. It's that middle point between usage within a single method (anonymous types) and usage in the external API (model classes).

I try not to leak Tuples between classes: it's easy enough in the API for your class to "unsplat" your tuple usage in any method calls other classes might need.

Also, Tuples are likely to become even easier to read/maintain in C#7 or so, as F#-like syntax for Tuples is a strongly favored proposal: https://github.com/dotnet/roslyn/issues/347