I dont have that set up, but I am putting two FX5's on my 210g. After watching videos of the output of the FX5 with the standard dual outlet they give I decided to make spray bars. That thing is a beast! I am using 3/4" PVC for mine; bar length 30" per side, with 3/16" holes drilled out every inch. I have seen a few set ups with these and they look like they tame the current that the FX5 can create. This will make for some fun plumbing since everything is custom, but I think it will be worth it.
You can adjust the flow of an FX5 down as much as you want without damaging the motor, so technically they could go on just about any sized tank just fine. I ran one on my 90 gallon full blast and it wasn't an issue at all. It's a lot of flow but it's not like a hurricane. I run 1400gph power heads, that's a lot more flow than an FX5.
I'm currently running an FX5 on a 29 gallon grow out, full speed, one pointed at the surface, not really crazy current either, but I can definitely see water movement throughout the entire tank when I feed.