I really like the idea of writing the test for the higher level behaviour first, then iterating on satisfying it. I'm sure this will often save time by not building up to something that's misaligned.

  “I made up the term ‘object-oriented’, and I can tell you I didn’t have C++ in mind” [Alan Kay]
  And of course, you can safely substitute C++ with C# or Java here.

This is one of my pet peeves. I never really think of C++/Java as actual OO, in my mind they're 'class-based'. I think the other thing that's changed from original OO and what we have now is the the granularity. Objects were meant to model real-world counterparts. We still have those, but typically a codebase is dominated by 'machinery classes'. If we had smarter base objects, we wouldn't need so much of that.

Just wondering, Is there something that makes server-side 'component' units that combine a slice through the layers (controller-domain-persistence)? This is a much better organization than by layers.