Neale, I get what you are saying.. but I still think its a lot more hassle and clean up to tear a tank down to clean out the plates and tubes vs opening up a canister or hang on back filter, rinsing the media and running a scrubby brush through the hoses/tubes.. no need to drain the tank and remove the substrate!
As far as bettas and gouramis needing slower flow, I've found its not always necessary. They may need a few weeks to build up some muscle, but they can generally handle a pretty good current ONCE they are conditioned to it. That said, you obviously don't want the current so strong that their fins get torn apart, but I've routinely kept bettas in my standard 10x per hour turnover setups with no issues at all. The first week or two is tougher on them, and I turn the flow down while they are getting used to it, but you have to admit, when they are coming out of a little cup of water with NO current, any current is going to be hard work
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