I was wondering the same thing , so I e-mailed Roland support a while back , and there reply was:

"The Prelude / Juno-G / GW-8 , all share the same keybed and chassis."

I have played the Juno G , and although aftertouch is missing , ( same for Prelude and GW 8 ) , I found that the keybed has very fast and smooth action.

Extremely light touch , but at the same time very expressive , so much so that aftertouch was not missed on many of the voices.

Being an old organ grinder , the organ sounds could use some work , but they are very useable in a pinch.

Roland did not mention anything about the Prelude sound engine , but I would assume that the Juno G and the GW 8
all share the basic guts,

You have an all Arranger / a straight Synth / and the GW8 Hybrid !!

Later

Gary 