I think you have to ask yourself whether you want to keep the bag because you want it as part of your collection, or whether you want to keep it (or any other bag) because it's the practical decision (you need/want to use the bag). This answer varies from person to person, and some of us may have a combo type collection (bags that are specific for collection, as well as practical bags for every day use). I am a combo type person, a quasi-collector...so I can tell you there's NO way I will sell my Mandy (can't imagine that happening ever, lol!).
But...it's not a bag I carry often because I have this feeling it kind of looks like a log on me, lol! I don't like the way it slouches down to look like a log, but overall, I think it's a phenomenal bag.
As for usage... I'll be honest... I have enough bags to rotate daily and never use the same one again in a given year. :shame: Some of my bags don't even get used in a year at all, and I also go through phases. When I really grow tired and out of love with the particular bag, I sell it. I sold near 30
Coach bags over the last year, but mostly I've been selling off other brands I own as of late (since I have my Coach collection down to the bags I still mostly love for one reason or the other).
I know some people think it's absurd to have so many bags and not use them, but to me, that's just crap (and short-sighted on their part) because we are all different people. It depends on what YOU need and want, and not what someone else thinks. If you can justify keeping (or selling) the bag, then that's what you should do. That answer may change for you as time goes on too! I've sold bags I never thought I would, and I've also sold "too soon" and had to repurchase the bag. I would just make sure before you let it go that you really do want to sell it. I typically get the bag out and leave it in my office for a week or two while I think about it. Sometimes it does get sold, and other times it goes right back in the dust bag until a later date. Some of the bags are still in my collection too, and I'm SO thankful I didn't jump on the "SELL!" bandwagon and get rid of them!
Just take some time and make the decision that's right for you!!