Folks, I am tempted to use the FT-2800 software to program my FT-2600M, based on the similarity of those two radios. Question is, ifthis is
not a sane
procedure and does not work, will I bork the 2600M beyond recovery?
It's likely not to do anything.
You can try to download from the FT-2600, and if the memory map is identical to the one in the FT-2800, then it may even work. But most likely it will just tell you that the model is not supported.
Upload will definitely fail. Chirp has preventive mechanisms to not upload even if just the firmware version of the same brand and model differs from what Chirp knows, let alone if the model is unknown to Chirp. That way it won't be able to brick your radio.
When you try to download data from your FT-2600 using the FT-2800 settings, please collect the debug log as described in the Wiki. Even if it doesn't work, it possibly gives the developers some valuable insight.
73, Bernhard AE6YN