I use this microphone in my cajon. Placed in the base of the cajon on top of a folded tea towel, it handles the range from deep bass to top end snap really well. I have it facing the tapa (front).
It has added benefits that it doesn't pick up much background noise when in the cajon, so works well in an amplified live setting.
The microphone is heavy enough that it stays put, even when I play the cajon tipped back slightly.
I prefer this to using two microphones (front and back) as it balances the different sounds that the cajon can make. My cajon has the sound hole on the side (2 different tapas), so trying to use a microphone near the sound hole isn't as easy as when the hole is at the back.
This is a good and much cheaper alternative to the Shure Beta 91.