I too have the X4 and recently upgraded to the Audya 4( after having the keyboard) I find the X4 is an excellent unit, but the Audya 4 is much more..more styles, sounds etc..the only problem I have is that the Audya doesn't have as good of a chord recognition as the X4. So when using the arranger section, sometimes the chord I play isn't read and then the styles doesn't follow my playing...I don't think it's my playing, because I have other units, GEM Genesys, Roland Bk7m, and they follow me well...so that's my 2 cents..I don't think you'd be disappointed in the Audya, the live guitars and drums are awesome...but better than the Roland. But the X4 has some very usable styles and sounds..