Having just run normal modes so far where loot is assigned, getting actual gear tokens from boss kills is pretty common - half or more of our 8-mans get gear items.

In hard/nightmare modes where you can master loot, etc, how much loot does each boss drop?

HM KP drops 2 rakata gear per boss, 2 alien (can't remember name but it's the other BOP mat), and some schematics as well as 3 columi comms per boss. Oh, also drops "weaponmaster" and stuff like that.

I got to the 4th boss on HM last night, so this is just from that experience.