A slight diversion for my obsession: using a plain flip-flop to generate a sub octave will give a ton of aliasing - as much as if you made a square wave VCO with no thought to aliasing. Now, if you use it only for low pitches you can probably get away with it.
Also, every VCO I’ve tested that had a sub had no alias mitigation on the sub output, even when the other outputs are nice and clean. Although I’m sure there are some exemplary ones out there.
Of course the Voyetra-8 used a CMOS flip-flop to generate its subs, but being in the analog domain there was no unwanted distortion in there.