I totally agree with bigriver and Wolf. I've run a couple of ACs and I like the emperors FAR better. I run mostly emperors and penguins on my tanks along with canister filters.
When people have problems with Emp's it seems to be because they didn't have the intakes seated properly, didn't have the cartridges seated properly, or just didn't maintain the filter. Of course there's people that just don't like the design for some reason or happened to get a bad one but that can happen with any filter.