Digital BW, The Print

I'd be grateful for the benfit of other's experience with MIS 
Variable Tone inks. I've just converted an epson 1160 to a CIS system 
using MIS Variable tone inks (marketed here in the UK as Permajet 
VariTone Blax). I've previously used Lyson SG in an 1160(different 
machine) with acceptable results. But now I'm struggling to produce a 
good tonal range in darker areas, with blocking up of darker tones. 
One or two thoughts at this stage (before I throw the whole setup 
throught the window!):
1) How critical is color space setting in the print driver? (Lyson 
produced specific spaces for each papers and it was essential to use 
these settings for best effect)
2) What color space do other users print to?
3) Do I have to accept less 'punchy' prints with these inks?
4) Just how much individual tweaking do other users find necessary to 
apply in addition to Paul Roark's curves?
Thanks,
John Adey