I run 12 tanks and have full access to Juwel tanks but choose to build my systems from seperate quality items rather than go for the cheaper package option. My first two "proper" aquariums were Juwels and i was very pleased with the first but after a run of almost continuous disasters with the second which was Rio 300 i decided that cheaper certainly doesnt mean better.
The key thing to remember with Juwel tanks is that they are designed for the European market where fish keeping practises are very different to those in the UK, on the continent the emphasis is usually placed on plants with just a few very small fish as livestock and Juwel filters are perfectly geared towards this, but when used for English (and American) style fish keeping which is usually stocking the tank with as many fish as it can safely hold and then using the plants to make the tank "prettier" and as a tool to soak up a little excess nitrate the filters do not function as well and require a little more maintainance then most people are prepared to give.