Thanks r_1159 and Just Alex.
So I understand from your answers that whatever noise I hear in the shop, this is what I am going to have... fair enough. Thanks for your quick reply, I will go to the shop and try it again. First time I tried it, I didn't hear anything, but I was not trying to check this exact issue.
Korg EK-50 is cheaper here in Spain than CTX-5000, and same price than CTX-3000... if it is "decent" or not, I cannot say it. When I tried both in the shop, both looked great to me (but as said, CTX sounds got me since the very beginning).
Pradeep, can you also share your esperience about the noise of the keybed? Thanks.
Roberto