i'd go with Biochem. Purple Rakata thingies justify this enough. I craft Seizmic grenades for PvP on other character and if there is bad situation in PvE - like double pull or something, i just use them in PvE too. It gives 4 sec of CCed (flat on ground) mobs to a healer to cast some big heal and save the day
While I see how it could be useful. After reading this, like you said, you almost can't justify Cybertech over Biochem. Maybe I'll just do Sytheweaving. While probably the other two are more useful, I'm still not sure I can stomach going Biochem for a 3rd time. I can't make my toon till tomorrow since it's when I get home finally, but we'll see.