Frans,

You are right. It is difficult, but I think PA500 is the best choice. Not as expensive as XS6 or S910, with ability to modify sounds, 80 polyphones vs 60 on M50 and MO6, and most important for me, guitar sounds that are probably better than others.
I think XS6 is also a good one, but 700$ more, and I should buy speakers too, so I do not think with my needs, it worth it.
Any suggestion?