I try to spine my sections, but if there is an obvious curve to the blank, I'll put the guides in line with that. With the minimal impact the spine of the rod has with modern compsites (IMO), I would rather have the guides aligned with the curve of the blank. I normally use multi-piece blanks for 90% of my building, and straightness isn't usually an issue. So if I can fine a spine, I'll use it, and if I can't find it, I refuse to believe it will impact my fishing or casting (and I'm not too convinced it will impact anything significantly in any case). On a 4 piece 6'6" blank, you will probably only have to worry about the top 1 or 2 sections. But don't get too worried about it either way.

"Now then, anyone ready to open the argument of where the guides should be placed in relation to the spine?" Nope. I personally don't think it matters. You can make a good case for either one, but I think the spine impact is negligible in real world terms.