Best treatment for "Slow Processing Speed"? Provigil? (Modafinil?)

So my husband got the full battery of tests a couple of weeks ago.  He does have ADHD.  His most pronounced deficit was in processing speed.  I can definitely see that.

I did a little internet research on slow processing speed and medication.  I got from various anecdotes that the stimulant medications don't seem to work very well for that, and one thing that

*does* work is Provigil (aka Modafinil), which is not one of the standard ADHD meds. 

Does anyone have experience with treatment of ADD where slow processing is the major issue?  What was done?  Did it work? Has anyone used Provigil?

(His psych appt isn't for another 3 weeks.  I can hardly stand the suspense- but I surely hope they get him the right medication soon after.)