I would hold on to your Chanel and save up for the Balenciaga. Prices have gone up so much since you purchased your Chanel, and if you wind up regretting it, it may be difficult to get again.
I agree with this. I was in the same boat as you. I recently was contemplating selling my vintage lambskin jumbo, as I didn't wear it for several months, and I have several people already eyeing my purse and waiting for me to sell it! It's a beautiful purse, but it felt a little too "fancy" for my lifestyle, as I tend to dress casually and I prefer silver over gold (and the HW in the vintage jumbo is insanely gold!) But then I wore it a couple of days ago and instantly fell back in love with it. I also took into consideration that if I want to rebuy a Chanel jumbo in the future, it will be waaaaaaay out of my price range. I knew I would regret selling it, so I decided to just keep it.
I agree with the other posters who suggest wearing it for a while before selling it. Good luck in your decision!