@David Beltz I'm not a CPA nor a lawyer but do have a series LLC. I was turned onto it by a RE layer and have since placed 7 properties into them. I like it for the ease of filing and having one LLC and separate LLC's under the main as you point out. One small issue was finding a local bank that would bank with this structure, but that was quickly overcome.
A drawback is that anyone can see how many properties you have as they have to be numbered from 1- however many are under that entity.
A pro is it's easy banking and you file one LLC while they are all separate LLC's as long as you can prove that the monies are earned by different properties. Such as...you have 7 properties that share a bank account and your manager deposits a lump sum into said account. They should send you a monthly statement per property saying incomes and expenses that add up to the lump sum.
As long as you can prove what each house earns, then they are separate LLC's per my lawyer and accountant.
A drawback is how new this entity is and how little caselaw there may be.
Good luck!