The place of service should be determined by the status of the location where services are performed, not by whether the provider is employed or not employed, and it would not be true to say that if they are all employed that they would all need to be billing the same way - each provider claim should have the appropriate POS code based on each specific location where that service was rendered.
What you're discussing is known as 'provider based billing' and this is a very complex and confusing legal area - if you do an internet search for this term you'll find many detailed sources. Whether or not a practice location qualifies to be billed as a facility depends on a lot of factors, such as the ownership, governance, licensure, supervision of and financial responsibility for the facility and staff, whether or not the medical records and billing are integrated, etc - there are even 'public awareness' requirements that you have to follow to making sure patients know that a location is part of a facility. And to make matters more confusing, the CMS regulations over all of this have become more strict in the past couple of years. It's important to get this right or it could cause a lot of compliance and financial problems, so I don't recommend you decide how this is done based on a debate - your facility should have legal and compliance officers set this up and have a policy in writing and a system in place and not leave it up to coders or billers to make determinations about what place of service is used.
Regarding billing different place of service codes to different payers, this may depend in part on your organization's contracts with the payers, but I will say that although it may be acceptable in some cases to bill POS 11 with no facility fee if a payer requires it, you will need to be careful that you are not billing a lower charge to some payers than others - the claim billed as an office service would need to have the same dollar charge as the combined facility and professional claims that were billed to the other payer for the same services - otherwise you may be out of compliance if you are effectively giving a discounted bill to your commercial payers by not billing a facility fee.