So do you two have a wallet with these companies holding it for you and you access it thru their site, or running one on your own machine?
Aaron
I could be wrong, but I'm fairly certain that Electrum stores the wallet.dat file on the local machine. I poked around in the folder a bit and seem to remember seeing one.
The private keys for electrum is held in one's local machine. The cloud part of the system merely assists in the procurement of the blockchain, where one doesn't need to download it as opposed to bitcoin-qt. The only risk would be the existence of malicious systems where a forged blockchain is fed to the user, and thus fools the user in thinking he has more/less bitcoins than he actually has. No actual loss of bitcoin should be possible as far as I know.