Keep in mind that many smaller stations out of SIN are served by SQ's regional (read: narrowbody) subsidiary, Silk Air.
As far as I know there's no Star Alliance benefits offered when flying Silk Air.
Silk Air does however, recognize and participate in the SQ KrisFlyer program.
Just something to think about... make sure the places you will be flying to are served non-stop by SQ (or other Star Alliance airlines) and not MI.
Oh and let's not even start to talk about SQ's other subsidiary, Scoot...