Merlin,
One good point that Uncle Dave mentioned is that 740 is not suitable for easy and convenient professional live performance. Let me give you an example. If you want to transpose, you must select the transpose button first, then you must increase it or decrease it and then you must press exit. This is too much work to do for one simple task. All other tasks are the same even changing the tempo! Of course, you can get used to it.
The good news is that PSR2000 seems to be redesigned. I looked at it and it has different layout. So I need to try it before judging it.
For myself, I want my 10 sliders, they make my life very easy.
