Happened on a nice Matrixbrute sound today, using oscillator sync and oscillator FM together. Essentially syncing VCO 1 to VCO2 (the only sync option), but then also throwing in some audio rate FM on VCO1, from VCO3, with the dedicated knob in the audio mod section. The FM on most analog synths tends to get strange and atonal, notewise, but having the VCO1 wave being reset every cycle with the sync to VCO2 restores the note you are playing, and the fm translates as interesting overtones- FM style sound with predictable notes.
Some good territory with detuning VCO3 an octave or two down, and the sync works nice when you tune VCO1 up relative to VCO2. I like the audio mod stuff using the softer waveforms, since the audio mod generates new harmonics, like sine or triangle wave on VCO3 and triangle on VCO1, but there were also some nice sounds with the square waves, both on VCO1 and on VCO3 as the modulator.
