I would wonder what percentage of moisture it takes to saturated a clay/straw wall enough to cause freezing and thawing, in effect crumbling the wall. The walls are to be constructed in the dry season allowing enough time for them to dry before cold temps set in. I see a dry wall with protection very different than a pile of clay exposed and fully saturated with water.

I keep reading clay and loam being used interchangeably, just to clarify, I don't feel comfortable using loam. For some unknown reason, I can't put my fingers on, clay seems to be the better choice. So when I say clay I mean clay not loam.

Most systems require maintenance, it all depends on what level you feel comfortable maintaining the system.

At Fox Maple, Steve Chappell's place, I noticed they were using kerfs cut into the sides of the timber for the infill to key into, so when the shrinkage occurs there is some sort of blockage to keep old man winter a bay. These kerfs acting similar to the planks inserted as the frame goes up. I am sure that system is not perfect either.

Speaking of foam built into a infill wall system, as you point out frost building up within a wall could deteriorate the infill system leading to problems, as well. If the foam is not of sufficient insulating value, and there is moisture within the house trying to get out and moving into the wall system, it will hit the blockage of 1-1/2" foam board and build up. If the outside temps are sufficient enough to to freeze the moisture on the inside face of the foam, I see this as an issue to consider. This is just one of many scenarios. The point which I think has already been made, adding modern components to older technologies may have hidden consequences.

It is all ways fun to reinvent the wheel or at least attempt. If nothing else is reassures the old method still works the same as it always has, even with its, known, pit falls.