I´m running 1696 on an NSLU2 with few problems. I upgraded from 1586 because I needed the enhancements in the newer nightly. The only problem I have encountered on my setup is the need to disable automatic scanning. Scanning while serving music caused firefly to crash.
As the previous poster suggested you could downgrade to a previous nightly, but I would think about downgrading UNSLUNG from the beta 6.10 to stable 6.8. Running beta on beta is just asking for trouble.