Nothing is simple
I called Truma back today. They indicated that there is a pressure regulator in the cold water line that is part of the Truma package. They said that it regulated between 40 and 50 psi.
I pointed out that the Truma manual disclaims warranty coverage for unit failure caused by incoming water pressure that exceeds the 40.6 psi limit. Their response was that, since the regulator was supplied with the Truma unit, that the warranty would honor damage due to excessive water pressure.
There are a couple of issues associated with this response that are a bit troubling. First, the warranty is time specific and failure due to excessive water pressure, even if caused by the regulator delivering water to the appliance at 50 psi after the term if the warranty, will be the responsibility of the owner. The other issue is the reality that pressure regulators fail to deliver at the rated specification at a high rate out of the box and, even if they start out on spec., they often lose that performance over time.
Though I am aware that this unit has been used sucessfully in Europe for some years, my experience traveling in Europe suggests to me that high water pressure in domestic water delivery systems is not a rampant problem.
If the 40.6 psi limit is real, then the protection offered by the Truma supplied regulator is suspect, in my mind, because of the potential 10 psi excess allowed by the Truma supplied regulator. It is certainly possible that the Combi could function as expected during the term of the warranty, but fail due to excess pressure allowed by the regulator limit variability post warranty. Then again, regulators lose their rated specification over time with some consistency.
None of this would be troubling for the vast majority of RV water systems that are designed in the US to operate at 50-60 psi, but the Combi has an upper psi limit that was apparently significant enough to point out in the Truma manual with a warranty disclaimer.
Providing a regulator that exceeds that 40.6 psi limit is a bit troubling, in my view. It might be a slowly ticking time bomb that only goes off after the warranty expires.