definitely significantqualified
(These latter calculations are computationally feasible for DLPNO-CCSD(T)/def2-QZVPP but proved too demanding for canonical CCSD(T) even with the smaller def2-TZVPP basis set.) Once again, the improvement for W4-11 only contributes −0.022 kcal/mol to the change in WTMAD2, but an improvement of RMSD from 2.9 to 0.9 kcal/mol is most definitely significant for small-molecule thermochemistry.