At one point I had a magnum and a fluval simultaneously. The magnum was better for charcoal and putting fine particle filtration in, the fluval was easier to open and maintain, with better quick-disconnects. This was five years ago. When my magnum died, I went with fluval because of the previous good experience. I now have three of the fluval 404's and can economize on replacement stuff. The lfs
's around here push the eheim, but I believe it is because the profits are higher with them. They also ask $180 for a fluval 404, which is absurd since it is $89 online.
Let us know how the cascade works out.