EMMPs only focus on servicing your instruments cheaply. They do this without regard for current vendor or equipment manufacturer and provide less coverage than the OEM. Additionally, if a repair is too expensive, they will not cover it or they will drop coverage on that instrument.
EMMPs offer discounts while maintaining high-level service required to operate effectively and efficiently. EMMP providers base their proposals on costs and coverages as defined by the current agreements. These programs typically allow the end-user to select their service provider and even specify a preferred technician. In many cases, the clients will continue using the OEM for service. The only reason a client may elect to use an alternative vendor over the OEM is if they felt an ISO better met their needs.