... The last version of any particular release is often the most stable. Why not go back to Version 3.296? ...
That's not quite accurate in this case - it isn't a "generational" thing, but rather a "numeric" thing (as it was explained to me at the time by the AHP programmers).
The AHP version numbers start with "3" (the old ActiveHome was version 1.x, and there was a short-lived beta of a version 2.x for the CM11A that was never released).
The first version of AHP released was 3.142 (perhaps the "142" was a nod to the last released version of the original ActiveHome - 1.42, perhaps not). If you look at the Revision history (which was reverse-engineered several years later, and doesn't include testing versions that were never released to the public), the numbers just increment in sequence from there.
The "jump" from 3.1xx to 3.2xx (actually 3.199 to 3.200) was a minor revision - not a major one. The next number after "199" is "200." The same goes for the transition from 3.2xx to 3.3xx. (3.296 to 3.301 - there were a few revisions in between, but they didn't weren't good enough to get released to the public). I was told that every time they re-compiled the code for testing as a package, they incremented the number.
So, there was no deliberate change in the file structure from one version to the next. There were a number of "big" changes made (specifically to the DLLs and the SDK), that were not backward-compatible with earlier versions - you needed to update both the DLLs and the SDK at the same time). Not all of those were made at "convent" numbers. HOWEVER, since there was added functionality in many of the releases (and especially when they added the SoftStart support), it is entirely possible that an AHX file created (or modified) in a newer version of AHP will not work properly in an older version. The only way to know for sure is to try it.