Well we usually apply the term jellyfish to all three scyphozoa, hydrozoa, and cubozoa. It is a very loosely applied term. A man of war would still require a massive tank due to the very long tentacles.
if your still interested in a "jelly" type aquarium...look at monterrey bay aquariums jelly info page...very informative.. i like the small setup they use for their wind sailors...unknown scientific name to me...sorry.
but still way cool. good luck. also, feeding should also be an issue..right?
oo i read these guys are like polyps or some sort liek 4 different kinds =D wow four different kinds of Poplyps SEt sailed and wander off and sting anything they touch =D