The SMEG website was updated by Heliophobe with the following info:

The selfboot problem has persisted so I’ve given up on it temporarily.
Today I ripped out my arm7 sound core and replaced it with a new sound core on the sh4 side.I spent a lot of time optimizing that core, only to find it too slow and buggy for my needs. The DC’s ARM is just to slow to be used to generate audio streams in most circumstances, so I’ve put it to use manageing sound buffers.Anyhow, most sound problems have been solved. Space Harrier sounds right again, Alien Syndrome plays sound, the gaps in sample playback have disappeared, and the sound emulation doesn’t get stuck anymore

Sounds good to me and you can go to Heliophobes site here