Hi guys id like to say something in regards the way ST3 is heading as i have had past involvement in its rise,
As a sound engineer and musician i think multi track does help to improve your sound performance no doubt, but is it a great improvement to 95% of simple users that are happy with their backing track and use stereo output out of their ipad, iphone devices , NO to them it would just frighten them away as the software grows in complexity with no real value to them.
Here is what i think that would really revolutionize this software and that is LOOPING facility where you can break down the song in to segments and access each part of the song easily, this can be used in many different ways people that just need drum backing could use it as a drum machine, singers that like to add lib could easily move around the song to involve the crowd for longer if needed or shorten the song in a professional way by a button push,
currently there is software in the app store that can do this called TRAX i use this software only for a few songs as it manipulates the song file in loops very well but i can only use it on songs i dont sing as it has no lyrics capability it is not great but does what it does well.
The one thing no one has done yet is to have full control of BACKING , LYRICS, SONG MANIPULATION,
The only tool you can use for this is a dedicated Keyboard and a lot of them use Midi files to do this i have a yamaha tyros that does this it is $6000 and it is large to cart around.
ST3 has virtually replaced my yamaha as it can tempo change, and pitch shift, it has synced lyrics but one thing it cant do is manipulate my song on the run, i believe this is the next big thing that ST3 needs as it would introduce itself to a whole new range of customer.
Here is a photo of something i feel would make ST3 absolutely uneque 
If you think this is a good idea i will give you exact details of how i would have it function as i said this idea is not new it is something that a lot of keyboards are capable of but no one has built it in to a full software package that is simple and easy to carry to gigs.
Example
The method to create drum files is simple just record 1 bar or as many as you need of intro verse chorus fill ending as one song file
then segment it in to loops in ST3 and bang you have a drummer on stage.
You would then use an editor to segment the file in to loops in ST3
The potential use of looping is very well known it just has not been implemented in to software like ST3 yet.
Sorry to interrupt but i have been planing to mention this quite a while back but there have allways been other issues to deal with.
And now i have found a bit of time to compile my thoughts in a disorderly manner .
But Peter if you are interested i could give you a lot more in depth information.
cheers Damir