Greg, it's awesome that you're taking this work upon yourself. Aside from UltraStable, is there anyone out there using diazo sensitizers for carbon?
I actually corresponded with that fella from the dye-transfer post you linked to (small world!); I'll dig up the email and see if he gave any tips.
Out of curiousity, what was your tissue support & pigment?
update: How much sensitizer did you use? The DT-Yahoo! post says 4mL per 100mL, but in our personal corerspondance he says "250ml water, 15 ml gelatine, with sugar (amount appears to depend on humidity), and six drops of speed ball sensitizer". Perhaps you're adding too much?