In the frame of the HL-LHC upgrade, assemblies of two 5.5 m long 11 T Nb3Sn dipoles (MBH) are expected to replace 8.3 T NbTi LHC main dipoles (MB). Double and single aperture models, each 2 m long, were built and cold tested in operational conditions. The models have design features that are verified during these tests to provide feedback for the technology development of 5.5 m full-size magnets. With the last model magnets tested, using the final conductor, conductor insulation and assembly processes, the performance is evaluated and the readiness for series production is confirmed. In this paper, the test results of the latest model magnets in terms of training behaviour and memory, conductor limits, endurance, quench protection and other cold powering tests are presented. Additionally the results of cold endurance tests, thermal cycles and powering cycles, are discussed in view of the operational requirements in the LHC.