I still don't know why people go with a siding that requires future maintenance, specially with all the crazy vinyl sidings available today.
I have heard nothing about great things about hardy, but why want something you will have to paint at some point.. way off topic... sorry..
Because vinyl blows cow balls, that's why. The way it's installed, creats hundreds and hundreds of little holes for budpgs to make home in all over the house. It fades over time, and you CANT paint it.
If you live in an area hail is normal, a good size hail storm will trash the siding.
Want to add/change a window or door? Not as easy as pulling off a 1x4 piece of trim and going to town. Now you have to deal with j channel. And brick moulding that finished off a door won't always work.
Metal fascia and/or garage door jamb trim? Expect it to dent the moment you look at it wrong.
Vinyl is a cheap way out of replacing siding.
This is personal opinion only, your milage might vary.
I'm in new home construction and we use hardi. Not primed. Cut edges are primed as they are installed. Trim is all composite and pre primed. The houses look great once it's up and painted. I would certainly go with a cement board product and paint after it's up.