This would be a risky investment in my eyes.
If you knew for a fact you could have each unit fully occupied for as long as you own it, it still would be iffy for me. Repairs and Maintenance could really hurt you because your cash flow is very little. Plus even if you were to break even on repairs, the time you put in working on those repairs would not be worth it. Also, a 10% vacancy rate is not a safe enough number on 4 units. There are multiple things that concern me with this property numbers wise. I'm guessing it's a quadplex or a multifamily? Either way, 755k for 4 properties doesn't sound like they're the best properties. That also depends on the area but its hard to find a deal like that with the properties being in good shape. You should aim for at least a 10%+ cash on cash return (cash ROI). If you could send me the OM maybe I could help a little better.
In the end, this is your investment and not mine. Don't let anyone tell you, your investment is a bad one or a good one. Take their opinions into consideration but never let anyone tell you to do, or not to do something. Make your own decision off of what you feel is right. I am sure there is a lot I do not know about these properties which could change my whole perspective. From an investors-agent perspective on the numbers, I would look for a different property to put your time into.