I thought I should share my latest findings:
The above mentioned Monolithic Pitchshifter Preset
was giving me problems.
To simplify my situation,
I attempted to use Preset 5437 Multishift_4 instead,
which only uses 1 DSP.
I was able to successfully download this preset
from my H8000FW to my Mac.
Using VsigX,
at the end of the algorithm,
so that all signals end up only at Stereo Outputs.
I was able to send this algorithm
back into my H8000FW,
it compiled and loaded properly.
I sent audio through my H8000FW,
and the newly created preset does exactly what I wished:
4 pitchshifts for this preset, using only 2 outputs.
Unfortunately for me,
anytime I send any data using VsigX
from my Mac back into my H8000FW,
I get problem messages at startup,
which tell me it's Bad Checksum Error
over at Setup / Service / Info.
I guess until I acquire Virtual PC,
I'm stuck without VSIG.