I wont go into the long list of what was lost from the X except to mention the SRX interface for any cards you invested in on X you loose if you come from the X to the G which can hurt..
On the other side, what was gained on the G was
dedicated External midi mixer
DAW Controls/faders
USB storage with project based file system
Dedicated fx slot for every patch
larger lcd
Its wav library has also been updated with some of the SRX wavs
Faster load times
New pattern based sequencer which work great once you get use to it
USB Audio
VST plugin
Sound wise..
The addition of patch based fxs does help add a certain quality to the sounds on a patch level.
However little or no tweaking on the X can achieve the same results especially in the studio.
from the live point of view the G wins but in the studio they both have the same abilities when it comes to sound.
C'mon Quinnx, are you saying you are considering the idea to swap the G for a X ?
can't be true...
As far as swapping out the G for the X
Recently i have found myself using less on the G things like the sequencer, patch tweaking and mfx etc and as far and setting up for tracks i usually have some dedicated type instrument sounds i will use over and over so im not needing to do alot of tweaking and doing most of it externally so it seems that what im using less of leaves me with what already exists on the X and then some if you include the SRX Library installed.
Which is why its a consideration