Dry powder inhalers target optimal performance, but should also consider the robustness of the downstream processes. Blend compositions which improve Fine Particle Fraction (FPF_5μm/ED) hinder process yield (rejection rate, RR) and device performance (emitted dose, ED). This work establishes relationships between blend rheology, product performance and downstream process efficiency and sets a Design Space which integrates different trade-offs between Product and Process optimization.