I am half way through my setup of a 2080 on a 6x2x2, I have the 2080 and a classic 2217 with a 1.5l purigen reactor...my water is...well it looks like the fish are floating in air!! the tank is clean about 20 mins after feeding beef heart!
I would not ever entertain getting an FX5...I did 3-4 weeks worth or research into the 2080 vs the FX5, I rang so many aquariums in Australia through all different states and every one told me the same thing,
"We have stopped stocking the FX5 because we cant deal with the number that come back broken..."
As far as the 2080's Mechanical power...Im not that impressed, so to get round that I took all the bio media out of the classic and filled it with sponges and then the inline reactor with about 400ml of Purigen...