I have yet to buy a GS series, but I've had a D-2 since new and it's been a great cue for me. It looks like the major difference between the two series is the GS uses stained maple to get the various colors, whereas the entry level D series used exotic woods for the butt of those merry widows. The D-2 and 3 used Bolivian Walnut. I suppose over the past 40 years those exotic woods have become nearly extinct, or just too darn expensive for those types of cues. I think this is a major reason those C and D series cues are fetching such good money these days.