The measurement signal hasn't actually changed, just the way that start and end are shown in the signal generator controls to make them consistent with the measurement window settings.I see the measurement sweep signal is modified a little so I intend to update my external sweep file accordingly.
The meas sweep export needs an additional dialog to choose whether or not to include a timing signal and where, I haven't done that yet. It would also lend itself to a mode where REW can be set to start capturing and wait to see the timing signal before capturing the measurement, removing the complication of trying to time things by hand. On my todo listI looked to see if the measurement sweep export feature now includes a new option to save a stereo version of the sweep with the new acoustic timing sweep on the reference channel. I don't see that option yet. I am thinking that it will make it possible to run external sweeps that provides the capability of the new acoustic timing option.