If you want to run a batch file asynchronously it requires you to add a wrapper to execute the command with a min command. (Eg. START /MIN CMD.EXE /C C: empmybat.bat). It would be nice to have a parameter to enable an asynchronous silent mode.
This would be useful and a convenient option for FME - that way we'd easily have the option to either execute commands synchronously to integrate their runtime into a workspace, or execute commands asynchronously to more efficiently utilize FME with long-running processes.