Ok all.. here is what I've found! I did a clean/fresh install to an external disk as to not trash/upgrade my existing Mavericks install. After the install was completed I went to Avid's site to download the Eleven Rack drivers just to make sure I had the latest and greatest. The drivers installed with no issues what so ever.

Next I installed the Eleven Rack editor and the install went smooth. I did however run into a strange issue when trying to run the Editor for the first time. The Editor threw errors and eventually crashed out after reporting that it couldn't find a few particular iLok drivers. I tried to run it again after the first failure to see if it would get any further and did the same thing. Avid's KB for the editor mentioned that if you don't have the drivers installed, the Editor installer should put them in place. Clearly that wasn't the case. Since I do have Pro Tools I was going to need to install the iLok drivers anyway- so I downloaded the latest from the iLok site and installed. Once that was completed the Editor launched no problem.

I loaded and changed presets and tweaked some settings for a bit and had no issues using the editor.

I installed Pro Tools 11.2.1 and had no issues using the Eleven Rack as an audio interface. All looks good! The only thing that may be a drawback would be those that don't use Pro Tools and not wanting to install the full-blown iLok software. There may be a workaround for that, but as I stated- it wasn't a concern for me.

Anyway, this was my experience- I consider it stable/good enough that I'm about to do a backup of my existing Mavericks system and then do a clean install for real.... and of course...this is just my experience- you mileage may vary :-)