What I find quite strange is that I understood Heuer brought in the cal 15 to save costs quite late at the end of the cal12 era.

What is strange to me is that the 1563 is the earlier style 1163 case, whereas I would expect the cal15s to be in a later 11630 case.

Have I got this chronology wrong? Or is it just silly to assume a linear development where Heuer was much more creative (ie: random?).

On the value, I'd guess more than a viceroy and less than a siffert to start with, but that is a pretty wide range. Then you have the rarity / desirability issue. These seem to be much more rare than the cal12 silver dial (itself quite rare), but I don't know if anyone really cares about that unless you are an Autavia completist. Sorry, not much of an answer.