We have two of them here in Cali.. ET150G with 8' and 12' heat chamber.
LOVE THEM!!
They use a pressurized heat chamber to create an even air flow
The exhaust stack is only 4" so no need to cut this gigantic hole in your ceiling or buy that wicked expensive 12" exhaust pipe.
One of the issues with the older models, they use a quartz lens to 'view' the flame and when it gets to dirty, you have to clean the lens.
Easy on these new ones, the old not so as you basically have to disassemble the sensor.