Ive had no issues at mybitcoin before or after mtgox hack, so these claims about "mybitcoin changed my password" etc. seem highly unlikely.
Definitely makes alot of sense for them to steal your 3BTC but other users, including myself, have >1K in there.
Clipse, are you certain that's a wise thing to do? I would never use an account based service to hold large amounts of bitcoin savings. For savings, I would suggest that you need to have control over the ability to spend those bitcoins. Otherwise, you don't have any bitcoin savings, what you actually have is a contract with a company to deliver you bitcoins on demand. A small amount of spending money isn't bad, but >1000 BTC? Seems nuts to me.
I believe people are working (Stefan Thomas, justmoon) is working on a hosted wallet solution that would enable you to retain control of your coins while at the same time providing encrypted backup. Until then, I think the best option for savings is the regular client and great care over the handling, encryption and backup of wallet.dat.