A couple of extra observations:
I had trouble getting the .st image onto a floppy, which is 99% likely to be me working my greaseweazle incorrectly. But I dropped the .st file onto a USB drive, hooked up a gotek in the STE on my bench, and copied the files onto hard drive. Then hooked up a real floppy drive to go in the opposite direction: put the files on a floppy.
Upshot: the game actually runs great from the hard drive anyway! credits.prg bombs out from HD -- I figure because it's looking to call right into the game program which is in the wrong place -- but the game itself runs a-okay for me.
This machine also has an exxos 32MHz booster in it. Good news, the game runs fine under acceleration. One thing that I can't quite put my finger on is that the audio maybe glitches a little in this mode, but I don't have a side-by-side recording of that vs. the audio with the CPU clocked at 8MHz to convince myself. It does make me aware that there are probably some fixes I could make to this machine to improve the audio: in general, I get a few clicks and whistles that I don't want.
Otherwise, I tested exclusively on TOS 2.06, UK-english version on a 4MB STE.
If I were to want one feature, I think it would be a toggle for the chip music. The engine noises are a little low in the mix for me, and I kind of want to hear those good engine noises over the chip music!
Incredible work all round. Really happy to see this out.