I have not kept them before, however I have done about a years research and consulted people who have. I am looking for the hardier species (although I know none of them are hardy really, but some are more tolerant than others)
I currently have a 125 gallon tank that is running a fluidized bed and a canister filter.
When they have outgrown the tank, I am planning on building a 540g 36sq ft plywood aquarium (or near that - thanks to UARUJOEY for the youtube diy walkthrough)