Small thing, but I love how the console view jumps to the highlighted track you're working on in the track view just by selecting it in the track view ...that is SO cool , especially as the track counts start to mount and you need to jump back and forth from low track numbers to higher track numbers and vice versa ..Don't remember X3 doing that and its very handy

myself, I just love the core feature improvements.
I still use sonar like the day I started using it (with the exception of all the extras, like RX Effects, exc)
I simply like the core improvements like the one you described.
also the way you can scroll the console view and still be able to see the track names / numbers.
 
Its these improvements that make my life so much easier. don't get me wrong, I love the new features, new toys.
but im a ham and eggz type of guy. I record the same way I did when I had an analog deck.