I would buy used both ways. I just recently switched to a Luxe 2.0 from a Geo 3 and I loved both guns. Here are some pros and cons to each. Both have been 100% reliable in my time owning them while maintaining them at their directed intervals.
The Luxes shot is a little smoother and quieter. The gun is both a bit longer and slightly heavier than the Geo 3 and has very very good ergonomics with the molded front grip section. The bolt and eyes can be serviced without the need of any tools which is super convenient if your break paint or even just for end of the day cleaning. The high pressure regulator is a little more difficult to get into than the Geo 3's, but it doesn't need maintenance very often. The ASA on the marker is nice for a screw in ASA, but not quite as nice as the POPS on the Geo 3. The feedneck is excellent as is the trigger on the gun. The board is very nice for a non-screen board with every adjustment a person could want. I still prefer a screen, but talking board makes changing settings on the field pretty easy. You will want to wipe off and re-lube the bolt system prior to each day of play to prevent any sort of bolt stick or other issues but this is a pretty quick task with the quick bolt removal.
The Geo 3 is very light weight and an overall workhorse. Maintenance is almost completely tooless (need allens for the eye covers) and the gun doesn't require very frequent maintenance to stay running great. The bolt system is a bit less convenient to remove as you have to unscrew it by hand (oh the horror!) but it doesn't need to be done as often. The regulator can be disassembled almost entirely by hand. The gun is pretty short overall when compared against the Luxe. The ASA (probably the best design out), trigger and feedneck are all excellent. The shot quality as said above is not quite as good but no slouch either. I like the LCD board on Eclipse guns a lot and they have every adjustment a person could ever want.
The deciding factor for me was the ergonomics of the gun. I found the Geo 3 a little too short and the front regulator section a bit uncomfortable (very thin). The latter complaint has been addressed with the new 3.1 and its comfy rubber front section. The Luxe just feels awesome in the hands and your connection to the marker feels very seemless. It also has a very very nice shot feel which is always a plus. Best thing I could say is hold both and go with what feels best in your hands.