There are also people out there (of which I am most certainly NOT among the ranks..) that think it is okay to have no filtration. It is possible, but very, VERY difficult to go without a filter. It can be done, but not without a LOT of information and huge amounts of dedication to your tank...
I keep the extra filtration on my big tank to "split the load up" on each filter. The filters will last longer if they aren't working as hard... Plus, the failsafe factor.... I didn't have to worry about my tank crashing on me when my fluval finally kicked over because I had the emperor and the ugf to fall back on.
Also, I had some REALLY messy fish, and probably far too many for the tank size, but never had much in the way of water quality problems....