The H2D's independent dual extrusion covers the workflows that drive most multi-material demand: soluble supports, two-material parts, backup spools, and it adds LiDAR plus the 40W laser option. The H2C trades the second independent toolhead for the Vortek bay: six swappable hotends plus one fixed, no purge towers across up to seven materials, at the cost of some X-volume and $650 more.
Ask what your jobs look like. Two materials per part: H2D, and keep the change. Regularly three or more, or frequent material switches mid-job: that is literally what the H2C was built for.