Hi Keyboardfreak,

I have the Korg i40m which is an arranger module. Got some great styles and will play all i series styles as well.

Got a not too bad vocal harmonizer as standard and can be connected to guitar or midi accordian. Sorry don't have a weblink but the korg is cheap compared to the X4.

They are going for about £600 here in the uk now (not sure what that is in merican money

Just another option
Tony