QTR-Quadtone RIP

Hi all,

I used Matt's curves and got very good tonality results.
I haven't blend the curves yet, just used one at a time at 100%.
I would like to ask, since I remain a bit confuesd on tha matter, do I
have to convert in PS to any QTR profile same as QTRGrayLab etc or
simply leave the image as 8bit grayscale tiff and just apply the curves?

And one more thing. By using the settings exactly as suggested by
Matt, I get a white horizontal banding, actually one white line 2mm
thick, 2cm inside the edge of A5 paper.
Anyone else encounterd the same problem?

Thanks for your feedback
Zissimos