Digital BW, The Print

I am new to quad printing and have been experimenting with MIS FS 
inks on an Epson 980 using Somerset Velvet. I have been printing, 
printing and PRINTING! step wedges trying to get them right to no 
avail. The lower pat of the step wedge is not a problem to change and 
adjust. However the 100% to 60% range is very difficult to get smooth 
transitions (my print tests show the printer firing fine on all 
nozzles). At this point I'm a bit frustrated. Therefore I have 
several questions:

1) Does anyone have a transfer curve/work flow that would be in the 
ballpark for my setup?

2) I also tried the partitioned work flow and curves for the 1160 
thinking that it might be close because it is also a quad printer. 
However, the results were horrible - lots of postering. I thought 
there was no use in trying to tweak four curves if I can't even get a 
single transfer curve in the ballpark.

I would like to go to the piezo or rip drivers and eliminate these 
hassles but the cost is prohibative at this point in time.

Any helps suggestions would be greatly appreciated.

Craig