It's a wise purchase if you needed it (or wanted it) and use it.
I have the Rhythm Tech version of the Mini rack. I use cowbells, jam blocks and a mounted tambourine with my kit live and I also do gigs as a percussionist, so I get a fair amount of use out of my Mini rack.
I rarely use live percussion on recordings, since I prefer to use MIDI triggered module sounds (mainly to save "analog" tracks for vocals, guitar, etc.) - so I rarely use the Mini rack in the studio.