I had an EV-180 running on my 29g that I just took offline. The skimmer body is built like a tank, and that part should last for many, many years. The pump is the part that will most likely have the shortest lifespan of all the components on the skimmer. But with routine maintenance on the pump, I would imagine that you would see at least 5 years of trouble-free useage.
The skimmer body also requires routine maintenance. The insides of the skimmer get rather dirty, and once the skum in the bubble tower reaches a certain point, the skimmer's efficiency drops off dramatically. The injector piece has a tendency to have small particles get stuck in it which slows the skimmer' production, and the air intake can sometimes have junk get stuck in it. A good rule of thumb for this skimmer (or any skimmer for that matter) is to setup a routine cleaning schedule to keep protein skimming at optimal levels.
Hopefully, the maintenance tips I provided didn't scare you off from this skimmer, as it's a fantastic piece of equipment. Plus, this maintenance should be done on all skimmers, but for some reason, AquaC skimmers need more attention to maintenance than other skimmers in my opinion.