My wife and I would fall into this category. I have been keeping fish my entire life and this is the first time I have chosen to get involved in a forum....there are many people out there that just enjoy fishkeeping and don't partake in forums... a lot of the ancient fish didn't know the difference.
Our Mbu puffer is slighty less than 3 years old and was about 4" long when he purchased him (I "assume" it is a male, just because of his bright coloration but of course, have no idea how to actually sex one of these guys...). We kept him, until about 4 months ago, in a 48" tank with a bunch of Tanganyikan cichlids...
That tank, of course, is too small for the long run. We are presently living in an apartment while our house is being remodeled. His interim home is a 105G plastic stock tub...
His permanent tank will be a Marineland Deep Dimension 300G, which is 72"x36". Based on his size, that will be just about fine for him. When I last measured him, he was about 25" long...
I have never found him to be any more difficult to keep than any other fish. If anything, he is hardier than many of the smaller fish in the tank. Yes, Mbu are not for everyone but there is no "magic" needed to keep one, no special filtration, and yes, you absolutely can buy an over-the-counter aquarium that will work for one for its lifespan.
I also agree with whoever it was that said earlier that most care sheets were probably written by someone who only copied and pasted things off the internet and never has actually kept one of these guys.
Just my 2-cents.