Noam; If the suffix on the controller chip indicates firmware changes. My original CM15A has a different code in it from my later ones.
One of mine even has an IC socket in it for the chip change. As X10 was still trying to get the thing to behave.
If faded memory serves me. The old and newer ones I have. Handle the multiple commands remotes send differently.
Yes, it appears that X10 did update some of the design of the board, and some of the code inside the CM15A over the years. However, none of those changes could be "pushed" by the company, and updated by the consumer. I generally think of "firmware updates" as something that can be done by the consumer (either using a software package to write the new code to the chip, or by replacing a chip). X10 never did this with the CM15A.
Now it is entirely possible that as the newer version of the firmware was being loaded onto units at the factory, X10 loaded that new version on units that were returned to X10 for repair or replacement, but we don't really have any way of knowing that for sure.
In any case, I don't expect X10 to give us any way to update the internal code in the CM15A, which they never did before.
As for a software update for AHP, that's still a possibility. From discussions I've had with the developers ,lately, it seems they are still working on it.