Most modders use the xbox not just for gaming, but for movies, music, pictures, online gaming, and anything else a multimedia PC would normally do. It has
faster FTP transfer speeds than Avalaunch, can play
any video & audio format, plays streaming video/audio from a number of script-based websites, and
integrated Xlink Kai interface.
The only cons I can think of with XBMC are:
*Updates released almost weekly... with some having minor bugs (which cause lockup). If XBMC is set as your default dash and you upgrade to a buggy XBMC build, you would have to pull out the boot-disc to fix it. However, most recent builds of XBMC have been very stable, so the chance of this happening is small.
*Difficult to customize skin layout... specifically changing the "buttons" on the XBMC PMIII skin. Many .xml files must be changed to get custom buttons to work correctly. If you have widescreen, you double the number of changes.
*Folder-style menu is too basic... doesn't compliment the look of some of the newer skins. Having icons to view is nice though... very similar to WinMCE.
I think it comes down to experience as to which dashboard you use. If yer a noob... stick with Evox (just don't get made when people make fun of you). With a little experience, you'll move to either Avalaunch or UnleashX. If you're a gamer... you'll stick with those for ease of use. If you're a multimedia enthusiast or like to entertain guests, you'll love XBOX MEDIA CENTER.
Cheers.