TZFM is generally easier to work with, in that it doesn’t affect the perceived pitch (except the octave). With the DPO once you’ve got the expo FM timbre that you want, you need to carefully retune both oscillators to transpose it where you want it without losing that timbre (the Follow circuit doesn’t pay any attention to the primary VCO’s pitch knob, just the V/OCT input).
In terms of “tame” in a more general sense, the DPO requires a lot of restraint. It felt more prone to wildness than any other complex oscillator I’ve tried.
HD mk3 sort of defaults to well-behaved, but wild isn’t far away when you go looking for it. It does lack triangle, saw, square outputs but has phase modulation instead, which can reach some other shapes but tends to work differently with FM than oscillators that have those outputs natively.
In character they’ve all got different flavors, so I would hesitate to even guess at which would sound more similar or different to Rubi/Dixie. The one comparison I feel comfortable with is saying that Hertz Donut is a lot like Madrona Labs Aalto’s oscillator section, through part of its range… they can diverge pretty far though.