I can't help you with any local agents in the Baltimore area, but I would start with looking for an independent insurance agent because they will have more carriers to quote you out with.I can speak to the umbrella question. 

That way, if someone does try to get rich off your hard work, it will be your carrier and their formidable team of lawyers that will be dealing with it, not you racking up legal fees and stress.Happy investing,Troy

Although the owners of more than 20,000 properties expressed interest, differences over price, qualms by insurance carriers and lenders, and concerns about branding turned out to be major obstacles.

I would recommend going with an independent to check with many carriers. 

There are multiple reason why that is a bad assumption (that investor could be insuring that property at Actual Cash Value vs Replacement Cost, that property could be with an insurance carrier that no longer writes multifamily and the policy is grandfathered in until it switches ownership or that property could be under insured from the previous owner).  

@Theodora Precup - different carriers have different underwriting. 

Lastly, they factor in how often you SWITCH carriers.

Since then we have filed appraisals on each property with my carrier.

I'm a licensed P&C agent who works for an insurance carrier, and I can tell you from experience that independent brokers are the best option.

Nicholas,If this will be a rental property, the majority of the standard carriers will not write a property with an underground tank (active or closed) we do have two that will write it but exclude coverage for pollution.