A classical stochastic model of electron transfer is considered with a slow Markovian,solvent polarization mode and some faster (solvent or intramolecular) mode. It is shown that when the rate of nonadiabatic transitions between the reactant and the product states is comparable with or exceeds the relaxation rate of the slow mode, back reaction should be included in the stochastic formulation of the overall kinetic even if the free energy change of reaction, -DeltaG, is much greater thank(B)T. As a result, dynamical solvent control of electron transfer is to be expected in the normal region even in the presence of fast modes. In contrast, participation of fast modes leads to the reaction becoming effectively irreversible in the inverted region. The energy gap law is thus significantly modified. The relationship to the variational. transition state theory is established. It is demonstrated that spectral separation of the reaction coordinate into fast and slow counterparts is generally more consistent than temporal separation. As checked against numerical results for biexponential relaxation, the variational transition state theory offers a reasonable approximation for the rate constant in the normal region, provided that the activation energy is sufficiently high.