Open carry, in my opinion, is never a good idea. Tons of people will be turned off/intimidated by it.
Despite what the media says, your odds of becoming a victim of a violent crime are extremely small unless your a drug addict or gang member. It's not zero, but it's small. Now out of that small percentage, there's an even smaller percentage where the extra 1/10th of a second you get by carrying open makes a difference. Those odds are so small, it's just not worth the extra business you can lose.
Would you stop driving because of the odds of getting in a car accident? Absolutely not, you'd lose tons of business by not being able to get places. But you're massively more likely to get in a car accident than be in a position where open carry would've made a difference over concealed.
Whether or not you decide to carry is your own decision, but the real secret is to do everything you can to avoid a situation where you would ever need it. This means placing quality tenants, avoiding excessive displays of wealth in poorer areas, and most importantly, not getting involved in things unnecessarily. If you expect trouble, see if the local police will escort you, or do the job for you (in the event of evictions). If they won't, and you really do expect trouble, it would be worth it to pay some off duty cop to escort you, or if you don't want to spare that kind of money, a local bouncer. Shoot, you can always bring a big dog with you if you have one.
Will this eliminate your chances of being a victim? No, especially if you invest in lower income areas or rehab vacant houses where squatters swarm to. But you can avoid all but random attacks by just using your brain and sticking to sound principles.