Ok, I just re-read the article the OP was referring to in Photo Techniques Jan/Feb 09'. The authors were just determining whether or not split grade printing could produce contrasts and curves that are unachievable with a single filter. And they determined that it could not.
I haven't read the article but there's something in their conclusion that sounds flawed to me.
Originally Posted by brian steinberger
So don't let the article sway you from trying split grade printing.