I rode the bike to Ga-STOC last week and the FI light is back (code 26). I confirmed that my connection is still good and it's throwing the same code, so I have to conclude it's the ECM. I'll be on the lookout for a good used one if I can find one. There were no noticeable issues with riding the bike with the light on other than marginally reduced fuel economy. I'm disappointed, but it won't strand you so that's a plus.
Larry reported seeing more Codes on bikes loaded with electrical accessories. How is yours on this front?
And some on the GL side seem to believe a noisy ground on the Knock Sensor Loop could be affecting the ECM on the GL and trigger their Knock Sensor Code, could be same for the ST. So cleaning/fastening grounds might help. They also suggest running a dedicated ground for this loop, but I have no idea how their scheme would translate to the ST.
Reading Dark Sun on the GL side, it sounds like a failed ECM is a failed ECM. But if it is only just about to fail, its life could be extended by cleaning and regrounding.
On a side note, a local shop I deal with just procured a ST ECM for a client, directly from somewhere in Japan, but keeping details for themselves.....Sounds like there may still be some available out there if you are lucky.