I made it over to the Moog pop-up today with a half-developed plan to snag a Sirin.
it sounds plenty pretty, sonorous and bright. the bird namesake is well-chosen. was able to get to grips with some of the shortcuts (switching lfo shape) without any issue.
however, I also spent a little time playing with the grandmother, which sounded lovely and very raw. between the two, felt the grandmother was my clear preference.