The Pioneer Anomaly was only detectable over several decades and a journey to the furthest reaches of the solar system. I'd expect a useful propulsion system to produce effects quite a bit more detectable than that.
This effect is about 1/25 the power efficiency of the lowest power ion thrusters. Output at this level over a very long period might be useful at the interplanetary level and maybe at geostationary altitudes, but the low earth orbit environment is actualy highly variable and unpredictable at this scale of effect.
