I am not into chanel bags and dont think everbody needs one chanel to be classy or elegant or in style. I would not sell my LV for CC but I would let go of not used LV items if CC would be my dream ... It is personal preferance.
Personally, I wouldn't because I think long and hard before purchasing anything and therefore all the LV pieces I have I use and couldn't part with. If it's something you really want/need in your collection, I would save up for it. I've always wanted a Chanel, but I'm complete shock with the current price of the classic flap and don't think that bag is worth anywhere near that.
It sounds like you have a beautiful, diverse LV collection. I like Chanel, I enjoy my GST, the flap is very beautiful but you can't really fit a whole lot. Depending on your life style how often would you really use the flap? but in any regards, I would save to buy instead of selling your LV unless you fell out of love with your LV pieces already then if that's the case, yes go ahead and sell.