RE: Kinderzeat: tall enough for kitchen island?
No it not tall enough. One thing that will work on a kitchen island is a hook-on highchair. Though it depends on the type on island you have what hook-on chair will work. I never have used them before so I'm also not sure about what size child they can accommodate.
One other option I can think of is a booster chair that can be strapped on to your stools. You would need to make sure it's really safe if you go this route because your DS would be up pretty high.
Good luck
Michelle I
DS 1 - 7
DS 2 - 5
DD - 1