I 'love' how Ralph is resurrecting all these threads from 10 years ago... Ralph, the reason people use QuadTone RIP is because it allows you to have much more control over the ink levels and which gray inks can be used in the printer. I did some comparisons between the canned and custom P9000 color profile and a custom QTR gray curves and the Dmax increase was not insignificant (something like Density of 2.4 to 2.8). QTR profiling has come a long way in the 10 years since this thread was started. I've personally made several tools that make the process much easier than when I started with it back in 2007/8, and am about to release something that takes that even one step further (similar to my Dead Link Removed)