Yeah, I would agree they are definitely underrated. I have an 8" one. I'd say it is a really good starter ray. It's not a picky eater. Right off the bat it was eating trout worm and night crawlers. It doesn't seem to have the same type of teeth as a motoro, nor the same type of aggression some of the motoro keepers have shared about (ie motoro's killing fish that are much larger than them and even motoros that actively try to sting their owner).
Now that mine is bigger it has taken to eating market prawn too. I really enjoy my ray. I've only read of one person who has raised these up to large sizes, but it unfortunately passed away.
It's too bad they are not recognized with a scientific name. I think this would actually validate it's worth more.
On another note, perhaps we could keep seeing more updates of this unidentified species as we raise them up on this thread. I think it might serve as a great resource for other keepers of this underrated ray.
Best wishes to all those who have these cool rays. They are truly amazing creatures!