The answer is absolutely yes - with some conditions - the tunnel and instrumentation must be designed to work together at our Rn, etc. for direct results like stall, flow separation and the like to be useful.

However think of it this way. Every scale model we have flying today from the little electric models to the biggest gasser bombers to the turbine powered F-100 is flying in the big wind tunnel of the sky and all seem to work fine. I haven't seen too many full scale airplanes that couldn't be flown as models OK. So with that in mind even data from the NACA work, which is aimed toward full scale, can be useful for trends if not absolute precise values.