I have one pro 3, and two pro 4+, the only difference with the pro4 is they added a knob that when opened bypass the filter floss.
I rarely recommend going to filter floss as a media as it tends to wad up and need too much attention but I do really like the cut to fit "bonded blue/white" media as it has a stiffener built in.
But I bought a rather huge bulk roll of the blue white, fine coarse, bonded floss pad when Foster and smith had it on sale.
I use the floss pad that came with the filter as a template, to cut pads.
Using the blue, white pad pretty much eliminates the need for the bypass the floss option.
Getting one restarted if you didn't completely fill it with water can be a chore. I fill the canister, put the top on, pour water into where the hoses hookup,
until it is full.
I put the hoses back on, tilt it on an angle to get water to the impeller, and plug it in. Doing that cuts down on the number of times you need to press the primer. Then ease it back to sitting flat on the floor.
But the word noisy and Eheim, really don't belong in the same sentence.
I have one of the larger pro 3, and two of the larger pro 4, and all of the doors to the stand could be open, be standing right in front,
and you can't tell if they are running.
If you put your hand on one you will feel a little vibration, but they are silent.
Oh buy the way, I am defiantly an Ehiem guy!