Replacement for simPowerSystems Discrete Butterworth Filter block

I have models which use the simPowerSystems Discrete Butterworth Filter block, located in the library powerlib_extras/Discrete Control Blocks. However, in R2011b this block has been removed, and looking back over a few earlier releases I see that it was marked as "obsolete" although there does not seem to be any documentation to say why. Since it's no longer there, I assume there's a straightforward way to replace it. My trial-and-error attempts have come up with using the Discrete 2nd-Order Variable-Tuned Filter which gives the same outputs as a 2nd order Butterworth if you set the input F0 equal to the cut-off frequency, and set the damping to sqrt(2)/2. Is this the best replacement for the Discrete Butterworth Filter, or is there a better and/or easier way to get the same result?