Not sure about the Bluefruit, but you can easily program/customize the Minimus using the free
KADE Loader software.
The Grayhill stick you linked is pretty good.
BTW you don't need to solder on the Grayhill joystick pins. The joystick pins fit snugly into .100" header sockets like
this or
this. The spacing is wrong to fit more than one pin to a connector, but 5 individual connections works great. These box-style socket pins can be easily removed from the connector body.

CAUTION: The joystick pins aren't quite long enough to work properly with the commonly used ramp-style
KK100-type contacts like this.

If you're interested, I also designed an under-mounting method for the Grayhill sticks that allows you to easily remove/replace them.
Scott