Digital BW, The Print

Just trying to sort out the differences between these two ink sets. . . . 

Am I correct in saying that the primary difference between UT-3D and UT7 is
the tonality (i.e. "colour") of the cool toners and having a Lab a*
(selenium) toner instead of a Sepia toner in the Y position?

Would it work to put the Lab a* toner into the Y position in a UT7 set, and
then use QTR to create a selenium curve?

Last question. . .   Is it difficult to create split tones using QTR and
either inkset? I assume one would first create two curves, say warm and
neutral, to establish the appropriate settings for each curve. These would
then be "combined" into one master curve (the settings that is) with split
toning done by creating/importing appropriate Photoshop curves for the gray
and toners within that curve?

Thanks,

Terry.