Plex or XBMC or ? for Mac Mini HTPC

I have deployed a Mac mini to be used as a HTPC. It is physically in a different room than my Apple TV (3rd gen) and HDTV, so it is not directly connected with HDMI.
Currently, I run iTunes and use Roomie to play mp4 videos in the iTunes “Home Movies” library via AirPlay. (Everything is connected via wired Ethernet not WiFi for reliability and bandwidth).
Given the limitations of using iTunes for a video library (primarily, the difficulty of scrolling through a long list of titles and detailed guide information), I’m considering switching to a HTPC application such as Plex or XBMC.
I’m looking for recommendations on the best choice vis a vis tightest integration with Roomie.
Also, I wish to continue to use AirPlay streaming. I don’t want to mirror the Mac Mini display to the Apple TV using AirPlay; I only want AirPlay to stream the video/audio when a title is selected to play. Is this feasible?

I use XBMC I find it to be far superior to Plex in every way. It also integrates great with Roomie, showing the full meta data details as well as movie art. I run Plex on my Roku, only because it’s the only option I’ve found.

Having tried both, (Plex Media Server with Plex Home Theater front-end versus XBMC) I think I prefer Plex.
I’m not too excited about the XBMC user interface and Plex did a good enough job of picking up my library of videos. I don’t use either for audio or photos.
I particularly like the streaming support in Plex. Fire up any browser, and you can access it from anywhere. Very powerful feature.
Neither front-end can do what I want – redirect the onscreen display to an Apple TV using AirPlay.
However, I can use Plex on my iPad or iPhone and invoke AirPlay to get it onscreen without too much trouble.
I have found there is an app/hack called “Plex Connect” which would replace the useless "Apple Trailer"s app with a direct interface to Plex on Apple TV. It does this with DNS and SSL certificate tricks - no jail brake or other mods.
Sounds exactly what I am looking for - has anyone tried this out?

I currently use Plex and Plex/web to watch my collection.

I am thinking of dedicating a slim computer to be a Plex home theatre source. I am looking to build a small i5/i7 system with ir mouse/keyboard (hopefully almost never needed), and some remote to change movies, menus, etc. Since Plex Home Theatre uses JSON, I am hoping that Roomie will do a plex/home/theatre device, like the XBMC ones they wrote previously.

I did have an XBMC interface to my collection running on a Raspberry PI and it worked well, with the AEON Flux skin. But the XBMC interface is a bit too complicated for the female/non-techie in the house.

No matter Plex or XBMC you choose, you should know that they are not able to support iTunes library, since iTunes digital content are encrypted with FairPlay DRM technology, created by Apple. So in order to make less limitations on using iTunes library, you can use M4V Converter to help you firstly. Then you are able to freely control your iTunes library on Plex OR XBMC.