I haven't used the X-Box Music app recently but I pretty much use ModernMix for all the apps I use regularly, so I know what you mean about the convenience and not having the go back and forth to the start screen. I like to read up on the latest tech and have a few apps from various sources that I minimise to the taskbar while I'm busy with other things, and can access with ease in between jobs.
Along with Fences, Start8 and Decor8, ModernMix is one of the better apps Stardock has produced, and is right up there in terms of usefulness and ease of use.
Kudos to Stardock for simplifying our daily lives on the PC. 
