well DIKI since I have a T4 and perform with it 300 time a year I think I kn ow what I am talking about

the organ suite it a gigantic improvement
the Ensamble section will prove to be the best new thing by far
76 keys
a larger improvement in DSP much better a very Live sound
you can Voice style in right hand and play left hand bass seamless .
B3 sound a lot better, Piano sound much better new upright sound
did I say 76 keys that is worth all to me as a piano player it means a lot

by the way DIKI the guitar section a giant leap much better sounds and you can assign what ever amp style you want just like in the Kronos this is a very Nice Improvement Very Nice All the Guitar sound guys you will love this section endless opps

the emsamble section will prove to be the best part ion time for the novice players there is a harmony button that will give you a four parts with 1 finger this will be very popular for big band and acoustic type of stuff for those who can not play the clasics if you can this will open up a whole new world of opps being able to do a true string quartet in a wedding or a brass ensamble just a new way to make a buck and truly sound great . it will be great for me to do weddings ect and in the studio it will be fantastic .

mp3 and Midi file toggle just like PA3x this will be great for those who use songs and midi stuff like I do a lot a big Improvement over the T 4

So dont get me wrong here the T4 is still in my book a great Keyboard and I still have mine and use it all the time but we are talking a very large Improvement

I hope this answers your question . Ron