both are great devices, but factor in whether you need line-in recording and the need to use a cable to swap out your music, or a portable USB stick. the Muvo TX FM is only slightly bigger than the N200, and both have the same GUI and thumbwheel.
i personally like my TX FM better as i can't imagine when i'd ever use the line-in. the fact that i can plug this into practically any computer with a USB port w/o a cable is also much loved by thee.
oh, and the TX FM does come with an armband and rugged rubber case.