I'm not shunning or inventing problems. I've had 3 fluvals and have 3 eheims - the eheims work perfectly, never clog, keep the tank clean, the fluvals clog easily, don't prime well, you have to shake them to get out the trapped air, and they sometimes leak.
So quite simply - in my experience eheims are much better.
So quite simply - in my experience eheims are much better.