I posted a shot of this the other day, but I finally got the new 92mm fans in.
Size - The large fans fill out the 3" coupler near perfectly.
Airflow - Noticeably improved over the 5v 80mm fans. The listing states that these have about twice the airflow of the previous fan.
Sound/Noise - Barely noticeable with the lid closed. When the lid is open, it sounds like a server room. This was expected as these are 3500 rpm fans rated at over 60cfm. There is a bit of a buzz due to vibration. I plan to eliminate/minimize this with some foam under the PVC elbow.
Elbow and pipe for Lowes or Home Depot for about $15
Power adaptor - I went with this one as it is a switch style versus a transformer. This means lower power consumption. I also picked this one because it came with an adopter with terminal connectors eliminating the need for me to make solder splices or use barrel/bullet connectors. It has a 2A output capacity, so I can add more fans later, but I don't think I will need to. https://www.amazon.com/dp/B00VM292AO/ref=cm_sw_r_awd_ckLmwbY52CZM6
Fans - I picked these for the size and airflow. Price was good as well. I have some dollar fan guards coming from China in a few weeks. https://www.amazon.com/dp/B00H8UVJ00/ref=cm_sw_r_awd_qlLmwb9Z45EMY