The accuracy of various density functional theory (DFT) methods needs be evaluated for developing full-dimensional reliable PESs. Schaefer and coworkers evaluated the performance of 49 popular DFT methods for relative energies of the stationary points of the F + H2O reaction. Their calculations showed that all predictions by the DFT methods were significantly different from the benchmark values calculated by CCSD(T)/V5Z. Interestingly, the doubled hybrid XYG3 functional 105 has demonstrated accuracy and efficiency in describing several hydrogen abstractions, compared to the calculations at the CCSD(T) level. Encouragingly, the PES of the H + CH4 reaction, developed by the XYG3 functional, yielded QD results that were close to those on the highly accurate but expensive PES 107 based on CCSD(T)-F12/AVTZ calculations. Significantly computational costs can be saved by DFT, whose general applicability, however, needs further careful evaluation.