I produced a new firmware version that fixes the quirk reported in the previous post (mode not changed when recalling an onboard memory on a "far" band). It now uses a larger delay in the command sequence (200ms instead of 100ms) and the FT-817 seems to be happy with it and behave as expected.
All firmwares released since 2009-November-12 will carry the new delay. Freely available firmware for download will be updated shortly.
Thank to Cristian in YO-land for reporting the non-blocking issue.