I understand the concern.... I really do. I'm sure you Puffer folks see people all the time that fail to properly house a large puffer. So it's no suprise that the thought of a small group of MBU is nothing shy of rediculous... For the average fishkeeper.
One thing I have learned over the years here though is to never underestimate the determination of a ray keeper. Ray keepers are able to blur the line between hobby and lifestyle. It's VERY easy for me to justify building a tank of a few thousand gallons. IF my rays are properly cared for they can help pay for it with offspring. IF fish are putting money back into your wallet it's very easy to justify taking whatever steps necassary to insure continued success. Raykeepers don't skimp on housing requirements when you're spending $1K or more for a single fish. Nor would it be anything less then silly to underfilter or improperly maintain a tank with several thousands of dollars worth of fish in it. Don't get me wrong, mistakes are inevetable and shibby happens, I'm just saying hobbyists investing thousands on animals to breed, and have allready been successfull at it, tend to care a lil more then the guy with a silver aro, CK, RTC and 3 Pacu in a 125.
I think the fact that I already have a tank that's 10X4 and have grasped the understanding that they will need an upgrade someday speaks for itself.
Puffers may be a huge load to the average fishkeeper but for someone designing filtration for rays then it's different. The bio reactor that will be on the puffer tank will be capable of processing up to 5lbs of food per day and will be upgraded as necassary.