I have one...
I installed one 1. 5 years ago. Construction is high quality. They modified (lowered it) to fit below bed level at no extra cost. But, I believe I have a defective transfer switch as my fuel gauge will not show level of tank after switching while driving. If I shut down and restart, it will show the level. I beleive the PCM has to see a constant signal to keep reading the fuel gauge and when you switch it, mine I believe loses the signal and quits registering on fuel gauge.
I soldered connections, ran a dedicated ground and still have the problem. I've spoken and e-mailed AT several times. They last said i could bring it to their shop (over 500 miles away) for them to assess and repair.
I bought a FASS, so I'm not pursuing the AT fixing the problem anymore. I'm going to convert from aux tank to transfer tank w/ a dedicated fuel level gauge.
I would buy it for a transfer tank, but not aux tank again. Dif in price about $500.
Wiredawg