| I find Disciple pretty useless too. I don't usually bother with him. A well known online encyclopedia tells me that he was a last minute replacement for a different character, one who was dropped when most of Korriban was cut. If it's true, it sure shows...
Another way you can get a rough idea of your companions' INF is to go to the character info screen and switch back and forward between your character and his, watching the alignment bar. The closer his alignment it to yours. the more INF you have. If your alignments are the same, INF is maxed out. (Doesn't work with Kreia, though) | 
Linear Mode
