That's what we have on our exterior...one foot wide Hardie board applied vertically with 1x2 cedar battens. It's a modern house and about half of the exterior walls have no eaves. The house is 13 years old, and no apparent problems...and we live in the Pacific NW, so rain is a constant factor about half the year. I think the most important issues are having high quality, waterproof, housewrap properly applied, and making sure that all windows and doors are properly flashed. But that is true of any house. I imagine if you are particularly concerned you could have all the seams caulked where the cement boards butt against one another under the battens.

I appreciate you taking the time to reply. Your experience is reassuring.

You're welcome. Below is a picture of our installation. Look closely at the building on the right above the bamboo and you can see that, because of the wall height, we even have a horizontal seam on that wall because we exceeded the length of the longest Hardie board. There is an almost unnoticeable strip of flashing where the upper and lower panels meet.

As mentioned above, the key is a thought-out drainage plane and appropriate flashings.

Here is a link that might be useful: Building Science Corp. on drainage planes