I, personally, would keep it. I like to collect the less common Glocks. If it really serves no purpose to you. . . even just gratification from looking at it, then you may be better off selling it. I have a NIB G17 RTF2 that makes me smile just knowing it's in my safe. It's only NIB because I haven't had a range trip since I purchased it though. Gen 4 G21s are very easy to come by for the most part. G17 RTF2s W/ Gills are not so easy to find.
Final thought - You mentioned that you really don't "need" 2 G17s. In that train of thought, some people don't think you really "need" more than 1 gun at all. In my opinion, the Glock addiction is more about wants. If you want it, keep it and save for a G4 G21.
Last edited by madAB; 01-23-2013 at 23:47..