re: Non-experimental rocket planes...
That depends entirely on where you think experimental ends and routine starts?
One might cite the heavy instrumentation of a vehicle defining it a still in an experimental phase - but then how do you differentiate between simply having all the information to ensure a flight is safe, or having all the information to better understand the vehicles behaviour.
It's not even a line between the two, it's a transition such that one could classify every single Jumbo flight as 1% experiment and 99% routines - with the X-15 being 99% experimentation and 1% routine.
Doug