Digital BW, The Print

Two questions regarding the MIS Ultra-Tone inkset and Paul's curves:
 

1. Are the MIS Ultra-Tones a pure black-gray inkset where the intent 
is a truly neutral print? Or are the Ultra-Tones a variable-tone 
inkset, as was the "VM" product, where varying the printer-driver 
sliders could change the output from very warm to a coolish blue?

2. A year or two ago, when the MIS Variable Mix/Variable Tone inkset 
was the product most discussed, there were several reports of 
posterization caused by either (a) a bug in Photoshop 7 improperly 
converting grayscale to RGB (so some printed using PS 6), or (b) a 
problem in using the recommended sRGB workingspace, apparently 
resolved by using Adobe RGB (1998) notwithstanding Paul's 
recommendation that for purposes of his curves, sRGB was the correct 
workingspace.

What is the status of this grayscale-to-RGB conversion problem? I 
note that Paul's instruction for his NEW Ultra-Tone curves is to 
utilize the Adobe RGB (1998) RGB workingspace, not sRGB as with the 
old VM product.

Thanks for any responses.

Howard A.