Having watched a bunch of episodes recently, I have unfortunately concluded that my previous reasoning was wrong. I can't see Toby as SLI (he's more likely LII), while Darryl clearly is SLI. And I have no clue what Michael is anymore.

Wait... maybe Michael is IEE? That would make sense of a few things. Hmm. Actually, that would make sense in a lot of ways. Toby could easily be Michael's Supervisor. I'm going to have to investigate this further.