Miami is one of the few ports of Entry that now accepts the Mobile App http://mobilepassport.us/ system which is different than Global Entry (or Nexus). See the website for free registration.

Not sure if the Kiosks work for both the Mobile App and Global Entry/Nexus.

In PHL there were only six Kiosks for Global Entry/Nexus with no one in their line and we went through in about 10 seconds having previously gone through the hassle of getting Nexus.