While Bitcoin core is syncing, you should still be able to do a dumpprivkey in the console window. You can then sweep and import into a lite wallet like electrum.
This is good advice.
I personally don't have any problem yet, with Electrum.
Why there are some people suggest blockchain.info wallet for better to use
bc.i wallet is long time ago has been removed from bitcoin.org wallet list, for web wallet i suggest to use BitGo and don't store big amount on that.