I have Filstar xp2 on my 55 gal. I think if you were planning a heavy bioload you might want to go with an xp3. I have plants in my tank and am pleased with the filtration. I had 2 of the Emporer 400 biowheels on the tank before and am much happier with the results with the Filstar.
True..if you keep the tank topped off, you get less splash noise, but why sweat it? If I get some evaporation..which I do between weekly water changes, I have my return spraybar below the water surface..no noise.
Also...the coment about having the impeller properly seated is true. But once they get some age on them you need to get new impellers, they get noisey. I bought 2 at the same time. One crapped out way before the other one. I also has one that was hard to get reprimed for some silly reason. To reprime, you have to pour water into the part on the back, and I was rather sloppy at times and ended up dumping water behind my tank.
I think cleaning cannisters is much easier. To clean a hang on back you have to lift it over the tank..the cord is dragging...the intake tube hanging off...rather messy. With the cannister you just flip a leaver, the intake/outake tubes are disconnected, you unplug the thing and take it to the sink and break it down.
Now that said...I've only had this going for a couple of months and don't have the wear on the cannister that I did on the Emporers. I had them going for about 3 years before the great kitchen remodel disaster that made me take my tanks down.
What I would like that neither does is to skim the surface and clean it. I'd be interested in hearing suggestions for that.