Authors explicitly declare BOTH one-step and two-step DIFF-GMM their preferred estimations (selected via AR(1)/AR(2), Hansen and instrument-count diagnostics; SYS-GMM discarded for too many instruments, LSDVC for residual serial correlation); abstract headlines the DIFF-GMM SR (-0.26) and LR (-0.37) elasticities, so the preferred SR rows and their Table 7 LR twins all qualify. || "Therefore, the DIFF-GMM estimations (both one-step and two-step) are our preferred estimations. They are very similar to each other and, thus, there are no efficiency gains when using the two-step estimator." (p. 20, printed page of IEB WP; abstract, p. 1 of the numbered text, adds: "Price elasticities in the preferred model are -0.26 (short-term) and -0.37 (long-term).")
Romero-Jordan, D., del Rio, P., & Penasco, C. (2014): 'Household Electricity Demand in Spanish Regions. Public Policy Implications.' IEB Working Paper 2014/24.