Try to reduce 3rd pary risk as much as possible. If Coinbase went down, all your shares go with it. So use an address you genuineley control. I used Armory on an offline computer. As armorys message signing is not yet compatible with the signature process anyone else uses (soon to come) I am also using another wallet on this offline PC just to sign messages with this private key. Once I signed the message I can take it to the online PC by USB stick. So BitFunder can go down, so can Coinbase or any other online wallet. I can still proove I am the legitimate owner of these shares.  And as most likeley dividends will be payed out to this address I feel more comfortable to not ave the private key on any online computer. Hope this helps a bit.