An Advanced Metal Organic Chemical Vapor Deposition (A-MOCVD) process has been developed to fabricate REBCO tapes with critical currents over 6200 A/12 mm (engineering current density (Je) = 5200 A/mm^2) at 4.2 K, 15 T which is 7X the Je of commercial REBCO tapes and 5.4X the Je of best Nb3Sn tapes. Such high performance is due to the excellent growth of 4 – 5 µm REBCO thick films and embedded nanoscale defects of density of about 10,000/µm^2. By modifying the defect density, a critical current of 1440 A/cm has been achieved at 65 K, 1.5 T (B perp. tape). Flux pinning characteristics in these thick films has been investigated over 65 – 4.2K and 0 – 14T and correlated to the film composition and microstructure. 2D-X-ray Diffraction (2D-XRD) is used as a valuable metrology tool to rapidly screen the thick REBCO films for size and alignment of nanocolumnar defects as well as an in-line quality control system in Advanced MOCVD to produce consistent high-performance REBCO tapes.