I haven't yet. I wrote out a plan to tackle this, but have lacked the free time to start on it.

The overall plan I have is this:

The iTunes library on one of my machines remains the source of truth. All new music starts here, being a CD rip, or purchase.

The central library will sync to the iPhone as normal, and via iTunes Match, also give me access remotely at work or other locations.

MP3toFID will be used (Thanks dbrashear for fixing it to work on OS X) to sync from the iTunes library to the empeg. My plan is to tweak the layout to match my old empeg strategy of this:

For any AAC files encountered, I'm going to transcode them to FLAC (upgraded the empeg to 3.0). MP3s will just go across as normal. I may reconsider this if space becomes an issue, and transcode AAC to pretty high bit rate MP3.

I haven't worked out where I am going to store the mp3tofid links, this may be on the Mac directly, or on my ReadyNAS. The NAS also may make it possible to run the mp3tofid process and transcoding on it, instead of the Mac. For syncing to the emepg, I'm going to try and find my old Linux scripts that autodetected the empeg on the network. In the past, it used to auto update hijack, and adding a sync process here could work nicely.

Not sure when I will get started with any implementation, but I'll continue to post progress here, and consider hosting my work in progress on the empeg github setup. Just need to also sit down and wrap my head around git, since it's so radically different then other source control solutions I've worked with.