The need for greater flexibility, tunability, and performance has led to the more recent development of IR detector materials and technologies based on an array of Sb-based III-V compounds and structures. While these approaches have proved successful for some applications, practical limitations related to accessible materials properties and integrable combinations still exist. To provide a larger materials palette from which long-wave (8-14 μm) IR photodetectors may be produced, the use of high-quality metamorphic (i.e. strain-relaxed lattice-mismatched) virtual substrates that provide access to lattice constants between GaSb and InSb is of substantial interest. To this end, we are engaged in the investigation of multiple metamorphic pathways via MBE and MOCVD based compositional grading to support the development of high-performance InAsSb long-wave IR photodetectors. These efforts are focused on two main avenues: (1) a novel digital alloy approach for MBE-grown AlInSb metamorphic buffers; and (2) MOCVD-based growth of more traditional InAsSb compositionally-graded buffers. In both cases, preliminary work has resulted in threading dislocation densities at target lattice constants on the order of 1-3×10^6 cm^-2, with room for significant further reduction. Initial prototype InAsSb nBn test devices (8 μm cutoff), grown via MBE on AlInSb virtual substrates, have yielded dark currents as low as 3×10^-6 A/cm^2 (at 0.3 V), an order of magnitude below the equivalent “Rule 07” HgCdTe value, indicating strong promise for the development of high-performance devices. At the conference, we will present up-to-date results on the metamorphic buffer development and integrated devices for these two promising pathways.