Given the effort involved in disassembling a Mac Mini, many users will be better off getting inexpensive external USB dongles for wireless networking and/or Bluetooth, rather than trying to replace the internal card. This is especially the case if you want to run the Sierra compatibility hack. The main reason to replace the internal card rather than using a USB dongle is to ensure that WiFi is enabled at boot time, rather than at login time, which can be an issue for some (all?) external dongles.

The default position of the sleep light and IR sensor connector assembly is directly over the hard drive breather hole on many replacement hard drives, including Hitachi Travelstar 7K500 and 5K250 models. Other brands also have breather holes in similar places. Be careful not to cover the hole with the adhesive portion of the connector tape, as this can interfere with proper operation of the drive. I was able to reinstall the cable twisted at a slight angle in order to keep the hole open.