I've been looking into high pass filter design.
I'm looking at a basic Sallen & Key format with two two-pole stages switchable for 12dB an 24dB per octave.
The advantage of this is simplicity in design and also it's easy to make one stage variable frequency to tune the response (e.g. set one stage to ~30Hz and the other variable, say 20-50Hz).
A two-stage butterworth or chebyshev filter would give a sharper 'knee'. This does mean looking at gain greater than 1.
My thought is that the 'cost' of going to chebyshev is even higher gain and a less flat curve for the pass band.
While 'gain is good', ideally a filter like this should have gain close to 1 for the pass band so what comes out is essentially what goes in. Too high a gain means it could run out of headroom on transients, which defeats the object of the exercise.
I plan to use a charge pump to get +/- 9V to get plenty of headroom.
My thought is the butterworth arrangement (very flat passband, relatively sharp knee) is ideal, and tune it to have knee at about 30Hz by tuning for -3dB in the mid-low twenties.