I have used AI since... almost the first version. Our bosses many years ago went with Free Hand for a while instead of Illustrator. At the time Freehand actually had more/better features.
My problems with AI compared to AS come in specifically when switching from one program to the other. I wish AI had AS features... I wish AS had AI features.
The main thing that always gets me is connecting "fills". In AS you can have two filled shapes that share a single vector at the join. In AI you have to have two complete shapes right next to each other.
I just have to laugh at myself when I go back to AI after a long time away from it and wonder why I can't connect the end of a line in the middle of a closed shape.
I swear this happened. I spent a while struggling with AI trying to remember how to do this till it suddenly hit me... I can't. I had to laugh as well as cry.
I also switch back to AS and press the space bar to drag the view... then the animation starts to play.
-vern