As said before and before, Sonar is geared more for recording and mixing. Sonar will never be a full fledged notation program as Sibelius.
It seems like you have beeen waiting for this for 6 or 7 years or so. If i was you, i would stop waiting. It isnt going to happen.
If you look at the track record beginning at the first version of cakewalk, you'll see that natation has stayed the same, for the most part. They never claimed to be a notation software and by looking at the big picture through the 15 years, they never will and that is just fine with me.
You may want to pay allot more for sonar upgrades, if notation was better, but i wouldn't.