I can also daisy chain self powered devices all the way up to the g-raid mini being last and it'll still maintain bus power (I still don't know how Apple managed that one). So far i've only tried with three devices.
G-Tech drives have those super annoying stickers over one of the screws that you should be able to take off cleanly by heating it up but the one drive I took apart was out of warranty.
But yeah once it's out of warranty the g-tech guys on the creative cow boards encourage drive swapping if necessary, although i'm not going to wait the three years for my warranty to go out- i'll probably switch to high capacity SSDs once I get the funds.