Reversibility - also called repatriation. There are a series of issues with moving a service in and out - one is covered off in your next point about 'knowledge'. Protections can take place through contractual terms and conditions which speak to 'rights' to equipment, policies, procedures and staff. The same holds true when moving from an incumbent to a new vendor. To be successful going in , your must plan your way out.
Control is established by the client.
If the outsourcer isn't providing the proper information to the client, they won't have a client very long. May as well hang yourself. Objections like these show that the people you have spoken with either have not experienced outsourcing personally, or have had a poor experience with it.