> My hangup was that I don't think this really going to increase compatibility with user code

It's not so much about compatibility as default behavior - a simple `%gui qt` should not change how PyQt behaves.  If users want *non-default* behavior, they can always do their own imports/config, as you say.

> it sounds like the fix is to change the QT_API_PYQTv1 requests in qt_for_kernel to a new QT_API_PYQT_DEFAULT, and to modify load_qt accordingly.

I think that's exactly right.