B) If you have a project that demonstrates particularly egregious typedef behavior, particularly if that behavior is still around in LV 2013, R&D would be interested in taking a look.
NI Applications Engineering Department now has a sample project which they've confirmed shows the "Type Definition modified" behavior, it is attached to CAR #451107.
I'm also glad to report that with current 2014 beta, the use case I posted in the original post (add a field to a typedef'd cluster, or change fields order) doesn't trigger changing the VIs that use the typedef.
Deleting a field or changing name/representation stilll triggers VI change, which I can understand.
Great news for me! Thanks guys!
So this explains that odd saving of unchanged code when going between computers. For some reason I have been trying to get away from using strict typedefs lately -- now I know why.
One thing I do after changing a typedef, when I want them all to look the same, is make it a strict typedef, apply changes, and then go back to a regular typedef, apply changes, and save all. Yes, it takes a few more steps, but (hopefully) eliminates the strict typedef problem.