I would like an answer on this also. I've read dozens of pages on this subject, all with varying opinions. The EB FAQ says to adjust the neck.
My JPXI came with an almost straight neck. I had to give it slight relief to stop some buzzing at the 5th fret, but now the higher frets are just high enough to bother me.
A neck with little relief (i.e. "too straight") may require higher action at the saddles to avoid fret buzz, but that makes the strings a little higher at the higher frets. So, if the action is too high at the higher frets, I first lower the saddles. When fret buzz becomes bothersome on the lower frets, loosen the truss rod.