Hi Peter,
that's a very difficult question as I don't have had a Tyros1. I advise you to ask that in the Yamaha-forum. I bet there will be a few which make that step. Of course I heard the difference on those 2 models and the people I have spoken says that it is quite a difference. But it would be a shame if the keyboardtechnology had stand still last 3/4 years, wouldn't it?
For some reason I recognize your doubt. I had that when I had a KN6000. I was very satisfied and thought: better is not possible. And than came the KN7000 and I had to choose again and I made the update, which I don't regret. Don't forget: it had also to do with the trade-in value.
Sometimes I'm glad Technics stopped, so I don't have to make such choices any more (for the time being ).
For what it is worth my personal opinion to the KN7-T2: the gap between the KN7000 and the Tyros2 is not that large, that it stimulates me to change. But I can't garantee that when the Tyros3 or .. is coming about 2/3 years
And believe me, whatever choice YOU made for yourself, will always be a good choice,
Happy keyboarding,
Cees