Low output impedance is important for active filters (which is the original intent I think), to obtain the expected -3db frequency and filter response curve. The reactive loading of the filter combined with the high output impedance of the follower will make for some highly unpredictable results.
This is not as much of an issue if used AFTER the filter, and this circuit will indeed work fine, but not as good as an op-amp in areas relating to PSRR, linearity, and input impedance. The noise performance will be better than most op-amps tho'. Just my 2cents