There is a line of thought circulating among LLC commentators suggesting that Series LLC formed under the Delaware LLC Act not only creates a liability shield for the LLC against claims against a series (like a traditional parent-subsidiary corporate/LLC format) but also shields each series against claims against the LLC (not available to parent-subsidiary).
Take a look at Delaware LLC Act Section 18-215(b) and see what the fuss is about:
"...none of the debts, liabilities, obligations and expenses incurred, contracted for or otherwise existing with respect to the limited liability company generally or any other series thereof shall be enforceable against the assets of such series."
Fortunately or unfortunately, Iowa's new LLC Act does not have this language. And of course, there is no case law on the subject.