I have been using the HOD in my XF/XXF tipped pens-the flow is great, it's definitely darker than the regular Noodler's black, but unfortunately it's making the nibs run wider. It also feathers more than the regular black on the cheap office papers. Any idea how the FPH exclusive OMB compares with the HOD wrt the flow and the feathering?
I tried to do a search but didn't receive any comparative information.
I'll greatly appreciate any input.

Try the Ink review forum, and the scans sub forum there... The blacks have been reviewed, and compared.

Also the search tool doesn't like too short a term so try writing out the full names when searching.

As I recall the OMB is slightly "blacker" to some people than the HOD, but both are purportedly well behaved. My experience is cheap office paper doesn't work well with most fountain pen inks.

The two best Noodler's black inks for cheap office paper are the standard Black (which member mdblue has already tried) and the X-Feather Black. The latter dries more slowly. I don't know if it's darker.