I did/will :)
My puffer died recently so I'm down to a snowflake eel for predators. He's being moved onto my 120 later down the road once it's stocked a bit more. If I can convince the fiancé, the 120 will be all scorps, lions and eels with maybe a colourful puffer as the show off fish.
I have a 5 gal with a fortescue in it, but he's only an inch long at the moment. He'll be moved to the 120 when he grows a bit more. I had two, but one wouldn't eat so I let him go in the ocean.
I'd love an octopus and a cuttlefish one day too!