QTR-Quadtone RIP

What curve would people recommend for an Epson 1280 using K6 and Epson 
Premium Luster paper?
I have just installed the system and I am bascially testing and 
experimenting.
So far I have good results with Matt and William Turner on William 
Turner paper but when I try Premium Luster, one of my favourite 
papers, results don't seem to be as as sharp/crisp and some prints 
appear to be a bit washed out. The Premium Luster option is available 
on the 1280 UTC but not the K6

thanks

RR