>>  you can simply check your balance anytime

I guess my point is that coins are virtual, they are just numbers.   

and so if somebody steals your coins, you might still have them also.   there could be multiple copies of the same wallet.   they haven't vanished from your harddrive.   just a copy-and-paste operation .

And so, is the wallet smart enough to realize this?   is the online exchange smart enough to realize this?      in real time - not 3 months later when you attempt to spend the coins, and find out they are invalid now.

It seems like there are two common ways to lose coins:

1.  wallet is stolen
2.  there is a fork in the block chain, or major systematic problems with the whole coin system

next, it seems there are two ways to store coins

1.  in your local wallet
2.  on a major exchange website.

If we combine those two sets of choices, there are a few combinations.    For each of those combinations,  how do you find out that your coins are "gone"?    how will you know.       for example, would your wallet suddenly show "empty".   or you wouldn't know they are gone, until you tried to spend the coins.

thanks.

-newbie