I still prefer the piano bench style thrones, but that is because I use a big 76, and there are times you want to slide one way or the other (if both hands are at the top or bottom end) just a bit.

The form of the piano bench has been honed over centuries to address the needs of pianists. If you have anything larger than a 61, I still think it offers the best solution. And let us not forget, even 61 note keyboards (the organ, for instance) often come with a bench, rather than a stool.

A lot depends on your playing style... are you strictly a live arranger player, with one hand ALWAYS at the lower half chording like a madman and one hand ALWAYS at the upper soloing away, or do you play full keyboard, where your hands might occasionally be both in one end? If the former, a stool is probably OK. But unless you are prepared for an uncomfortable body position while you play both hands at the ends, a bench offers the correct shape.