I bought 3 little guys about 3" apiece back in late july. They are 7" apiece now so yes they are quite fast growers. I bought them to fill out the upper reaches of my tank to make it look more balanced. It's worked a treat because along with my chalceus they only inhabit the top 7 or 8 inches of water.
They will eat just about anything and are even greedier than my tinfoils which are renowned for being dustbins. Just be careful at feeding times, they are jumpers. A few months ago i was feeding the fish, left my lid up on my tank and just popped into the kitchen to get some food. I came back and one if my cigars was flapping around in my cats paws. I got there just in time before the cat sank its teeth into it.
The only other thing i can add really is they are a beautiful fish, very busy, and get along with all my other fish. I might have problems in the next couple of years though, these things will get huge and they are only in a 180 com tank. I'd hate to have to get rid so i might have to get a bigger tank!