You would be better off with a 6' tank with those guys. Either way, it's not a waste, but actually a necessity. Devil looks good, especially with the circumstances.
the 150 i want i think IS 6 feet, i could be wrong, but its a reallly really long tank.. i'll have to double check it at work tomorrow.. its long, wide and relatively shallow..
put it this way.. it looks big enough to let my 3 year old swim in it comfortably...lol i like the longer wider tanks better than the taller ones anyway, it gives the fish more floor space..