Variational transition state theory, within the canonical unified statistical model including multidimensional tunneling corrections, has been applied to derive thermal rate constants in the temperature range 80-2800 K for the title reaction and its deuterated counterpart in the low- and high-pressure limits. The analytical potential energy surfaces of Bradley and Schatz (BS) and of Yu, Muckerman, and Sears have been employed. In the low-pressure limit, the results are comparable though slightly better for the BS potential surface at the lowest temperatures. In the high-pressure limit, the BS potential surface is notably closer to the experimental data, which are only available at temperatures close to and higher than 300 K. The kinetic isotope effect (KIE) at room temperature is better predicted by the BS surface, although both surfaces fail to reproduce the experimental dependence of the KIE on temperature.