Cob: Better than a cob "sandwich"

[Bob]

Thanks for all the improvements on my suggestion of sandwiched straw.
What is important, i believe, is that the heat mass of the wall be on the
inside to stabilize the room temperature and act as a good heat reservoir
in a solar house..  
Various mixtures of an organic material, bark, straw, sawdust, with a
mineral binder that will also keep it from rotting is the direction we want
to go.
Probably the cost would depend not only on  what binder was used but also
what was easiest available locally.  
I wonder if a mixture of clay and gypsum would be more reasonably priced
and better than just clay and straw  and more durable than just clay and
straw.    
Would sure be great if someone could try different combinations and measure
their different thermal effectiveness and compare prices.  Surely we can
learn a lot from German and Welsh-Cornwall traditions but we can
undoubtedly improve on them.

I understand one of the problems with straw bales is they settle more and
longer than cob.  In our area straw bale is allowed by the  building code
only if it is used as a curtain wall.  This means one has to frame the
house first so that there is not much saved in building effort.

Isn't straw bale too new to have a track record?  Can we assume it will not
powder over time and lose its strength, something we know cob, with a long
track record will not do.  

Bob