I checked, 2.5.171 is the latest release. There is 2.5.173 available as a beta if I register my MAC address with Roku. The only difference according to RokuMike is the ability to play iTunes radio station playlists.
My SB just played for over two hours before stopping. When it does, it stops mid song and just disappears from my network, not respnding to pings or serving up it’s web config pages.
I’m running svn-1359, but I’m not sure that it’s a Firefly problem, so I’m probably straying too far from the original subject.