Read more about it, you are right.. the EQ filters (out of REW) could be fed manually into ToneWinner.What a dirac or a dsp can do is to correct the timing using delays, crossovers, parametric eq settings, levels based on a curve either its a pre-created or a custom. All these values can be fed to the processor as it supports crossover, delay (speaker distance), eq settings (300 supports 11 band manual parametric eq for all channels and 5 for each subs). REW data can be exported to text format and feed those values manually to the processor using these settings. Repeat till you get the desired result. Even a processor with inbuilt Audyssey or Dirac we need to do the same for manual calibration.
However I have a feeling that for an average user, just taking care of basic parameters like distance/delay, levels and crossover would suffice.