5unit is probably manageable.  20 unit is work I would think. 

Property management is also in place. 

I'm a local, CT based investor, flipper, and property management company owner.  

I think it would be beneficial to set up your own management company to manage your assets.

Investing in real estate in actually starting, managing, and marketing a company. 

As a property management company in Washington, we help owners navigate these challenges and optimize profitability if they want assistance analyzing their property or planning future strategies.

Keep systems in place for managing documents and contracts.6.

I manage 600 LTR for my work.

“it is VERY hard to screw up when buying i.e. a duplex in good condition in a desirable neighborhood and either self-manages or hire a quality PM to manage.”excellent point 

that we’ve learned in our 24 years, managing almost 700 doors across the Metro Detroit area, including almost 100 S8 leases:Class A Properties:Cashflow vs Appreciation: Typically, 3-5 years for positive cashflow, but you get highest relative rent & value appreciation.Vacancy Est: Historically 10%, 5% the more recent norm.Tenant Pool: Majority will have FICO scores of 680+ (roughly 5% probability of default), zero evictions in last 7 years.Class B Properties:Cashflow vs Appreciation: Typically, decent amount of relative rent & value appreciation.Vacancy Est: Historically 10%, 5% should be applied only if proper research done to support.Tenant Pool: Majority will have FICO scores of 620-680 (around 10% probability of default), some blemishes, but should have no evictions in last 5 yearsClass C Properties:Cashflow vs Appreciation: Typically, high cashflow and at the lower end of relative rent & value appreciation.