I've been running 2x Aquaero 5 Pro's for a bit now, but it's a little challenging trying to configure controllers.
Aquasuite appears to become confused and displays the device selection for the opposite Aquaero. After a while you can work through it, often with a few crashes of Aquasuite.

Also when calibrating sensors Aquasuite will sometimes freeze up.

I've decided to swap one of the Pro units to another machine and replace it with an LT and run it as a slave device. Hopefully when the LT is installed in place of the second Pro unit the problem will go away.
But I thought I would bring this up as something that should be looked at by the Aquacomputer folks.

Just an FYI.

Other relevant information:
The reason I have 2xPro units is because I had a pump go bad and take out the pwm of the Fan 4 header. At the time I decided to buy a replacement Pro until I could arrange for repairs of the unit with the damaged fan header. Meanwhile I thought I would run both units until such time as I felt like shipping one off for repairs. My cooling system has since expanded a bit and I've decided to run both a Pro and an LT instead of a string of PA2's, and because I want two fan headers with pwm capability.

Well that certainly changes things.
I still have to think it will be less hassle than running separate devices, unless or until they get some more bugs out.