330/12 Neck Relief

[Folkie]

I just got my 330/12 back from the shop and have a question about neck relief. Chris Clayton at Pick of the Ricks has informed me that Rickenbacker recommends that their guitars be set up with no neck relief (completely straight), so I just had my 330/12 set up that way. I've noticed that I have a harder time playing barre chords near the nut than I did before the guitar was set up in this manner. What is the rationale for having Rics set up this way, and is there room for personal taste in the way the neck is set? Also, how do the type of strings (ie. flats or rounds) come into the equation?