I've used the PAC-US444CN-1 (at our house) and fully native Mitsubishi thermostat/controls (at our in-laws). The converter is better than a simple 2-stage set up but is still not as good, in my experience, as the fully native one.
It has to translate a 2-stage signal into a fully modulating output, and it still seems to do a lot more on & off with high fan speeds than I would like or would be most efficient (as an aside, yes I have verified that the dip switches are in the correct position on the converters).
On the other hand, the unit at my in-laws tends to blow gently but consistently which is both more comfortable and more efficient.
It has to translate a 2-stage signal into a fully modulating output, and it still seems to do a lot more on & off with high fan speeds than I would like or would be most efficient (as an aside, yes I have verified that the dip switches are in the correct position on the converters).
On the other hand, the unit at my in-laws tends to blow gently but consistently which is both more comfortable and more efficient.