However, this might expose your operational LLC to risks associated with your rental properties, which could be mitigated by keeping them separate.Cons: Separating Y from X could provide an extra layer of protection.

If its done right from the beginning yes it adds a great layer of protection, but again - most do not do it the right way so its not providing any benefit.

It just adds another layer of complexity to the process, it will hurt part-time agents and drive many out of business, which is frankly not a bad thing.Buyer-side commission is now no longer set as a typically uniform percentage on MLS and fully negotiable. 

Layered entities can be tricky as most lenders will want to see a paper trail to show you have at least 25% ownership. 

It reviews a number of different structures with  the advantages / issues of each;http://www.mondaq.com/canada/x/334102/Capital+Gains+Tax/Are+United+States+Limited+Liability+Limited+Partnerships+the+Holy+GrailAdding anther layer of complexity is; how much are you generating in profits?

The MMLLC will add an extra layer of audit protection being that they are at less of an audit risk than SMLLC's. 

Many seasoned investors bolster their liability protection by using a layered approach.

Bleach with some dawn added , put it in a pump up sprayer and soak the floor and let it dry , then pressure wash the floor . ( Wear a good mask and have the doors open while doing it 

If we have a 401k checkbook LLC then it could fix the anonymity problem but it adds a layer of complexity.

Effectively, it just adds another layer.