I never keep very much money in online wallets. All it takes is the site to make up a hacker story about why your bitcoins are gone and you are out.
If you're keeping Bitcoin in mass numbers then it is not really that advisable for you to store your coins to an online wallet for it has so much risk in it. Only use online wallets for daily or weekly transactions. But if you want to save up that really large numbers of coins you have then it is pretty much highly advisable for you to store it in a cold storage or hardware wallets, just watch out for viruses though.