the 2001 Kodak Professional Photographic Catalog contains a comparison chart.
Compared to D-76, this chart indicates that HC-110 (dilution B) produces:
Slightly less shadow detail or true film speed;
Slightly finer grain;
Slightly lower acutance.
Apparently, HC-110 has somewhat more solvent action than D-76, but less than Xtol.
Opinions differ about the effect of HC-110 on grain. Some photographers report coarser grain than with D-76; others report finer grain. This is probably a function of dilution and agitation.
Opinions also differ regarding acutance, since many photographers report that HC-110 produces high acutance, especially at high dilutions. This is a function of solvent action, which is reduced by diluting the developer.
Where HC-110 really shines is in scientific work or push-processing, where film is deliberately overdeveloped to increase contrast and speed. HC-110 gives surprisingly little fog even with very prolonged development. In this respect it resembles D-19, Kodak's high-contrast scientific developer. I normally use HC-110 (A) for 10 minutes to develop gas-hypersensitized Kodak Technical Pan Film, which fogs severely in other developers.
Like Rodinal, HC-110 keeps very well and gives very reproducible results. It is a good choice when failure would be costly.