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Rossum's Mob of Emus does the harminic oscillator thing beautifully, and a lot more.
Doesn't have the fun sliders though.
It can give you six note polyphony and can sing sweet as a bird or tear your head off.
Outstanding build quality and precise tuning, at half the price of the Verbos.
But only six harmonics vs. eight with the Verbos.

The OXi Coral in also interesting, but it prefers to be midi driven and that's not the direction you're headed.
The upside is it also does VCF, ENV, and VCA without extra modules, unlike Mob of Emus.

I've not tried the Metropolix, mainly because I have a Frap Tools Usta and a SIG Inspiration Generator
to handle sequence-y duties. Metropolix looks like an excellent heart for your system.