The Prelude/GW-5 are made in Italy, the Juno-G in China, and the Juno Stage in Japan.

Would that explain the differences in keyboard quality?

I thought the Prelude and GW-8 felt okay...not quite as good as the S910, but reasonably responsive....they reminded me of the earlier E-series (E-20 etc).

I didn't play the Juno G, but I did have the Juno Stage at home for a day...very nice instrument, and a decent quality action as well.

Ian