Just did a Kaon run Imperial side. Don't know if we just had bad luck, but only 1 purple item dropped for us, and it came from the final boss loot chest. There were a ton of greens and blues, though.
if its on normal mode, the bonus droid boss drops 51 grade boots and final boss drops 51grade legs. If the item itself is not an upgrade, you can always take the mods and enhancements out of it and give to companions