The low G adds very little in the way of extra notes but, I think, a lot in the color of sound in chordal playing. It warms up the sound, which is very nice for jazz chording or accompaniment. Also, in some situations (in any style of music) playing chordal soloing the high G can get in the way of the melody. This can be overcome with very good technique, but still...
Low G works well for me playing classical (for the extra couple of available notes) and for the darker sound it gives me for most jazz.
Some people prefer Low G for everything. Some prefer high G for everything. Some may think my opinion is 180 degrees off. It's all good.
What do you think?