Well eheim makes better products over, better quality, german made and I've read much better reviews on eheim than fluval.
I don't know that much about the models but will look into them tomorrow if I have the chance for you, but ya the latest models have that new high teck computer chip stuff in them

sounds more complicated and break prone if you ask me, especially since it's the first model.
Ya price is expensive and the flow might be too much for a 50 gallon, though i think you need less flow on cannister filters than HOB.
Hope somebody else that has these can chime in with their expierence, I've only researched them a bit and looked and taken them apart at stores, will let you know what I find tomorrow. Have a look at eheim.com and hagen.com-look around on that site to find the products and fluval products
btw-whats the temperature
