FWIW In the spring of 2019 I bought a registered Angus heifer from nearby Woodhill Angus to experiment making some BWF with my Hereford bulls.   This heifer, Angus reg #19227609, had a DOC score of +25 which is very gentle and scored by Woodhill who I know focus on EPDs and I have  great trust in Brian's numbers.

This Angus cow was very docile and I never felt there was any problem with her attitude. Same with her BWF calves. However they were very different than my full Herefords. Always a little standoffish and more conscious of me and what I was doing compared to my full Herefords.  I decided to stay full Hereford and sold her a couple years ago.

As far as needing a few Angus to help "move [my] Herefords along" - my herd is 98% or so grassfed. I do give them an occasional (usually once a month or so) few lb/head of a sweet feed in bunks in my corral as a training exercise. All I have to do is to stand near my corral, call them and bang on the empty white 5 gal bucket and a few cows with a sweet tooth will come galloping from wherever they are, even in the woods, down the hill and into the corral with the rest and calves not far behind. Close the gate and they're ready for the vet or trailer.

If I need to move them to a pasture farther away, all I need to do is to put a couple buckets of sweet feed in the back of the Ranger and they will follow me anywhere!

It is interesting that Herefords don't even have a DOC EPD. Granted there is a difference between Hereford bulls but this is where buying from a reliable breeder comes in.

And as a bull ages his attitude sometimes changes for the worse. BTDT with my Simmental bull experiment (ASA #3139561) who BTW had a DOC score of 9.4/55% as a yearling but turned mean and very dangerous. Not one of my better ideas. And his traits followed to his calves. Took me a long time to get the last traces of this bull out of my herd.