Hey Mario. I use similar numbers to your in my analysis (cap ex and repairs at 15%, and 8% property management, same vacancy). For my deals I like to Brrrr and end up with 100-200$ profit per door after refinancing my money out.
But don't let only the cash flow determine if it's worth it. Use CoC return and IRR to help determine that. $100 monthly profit is good if you have no money in the deal, but it's terrible if you have $50k in it.