The test target that came with my custom 1911 was shot with 5.1gr WST under a 200gr LSWC. The 25 yard, bench-rested, 5-shot group was 0.580".
Needless to say, I have not been able to duplicate that precision with any WST load, or any other load for that matter. WST is undoubtedly a good .45acp powder, but I found it to be no better than W231, Clays, or Titegroup.
Like you I recently started experimenting with WST from W231. I wanted to try a lighter bullet and a new powder. Not sure why because the 230gr FMJ and W231 worked fine. Always looking for the pefect combination I guess.
Using 5" bbl and 4.9gr WST behind a 200gr FPJ RN bullet I get 842fps making a 168 power force for IDPA.