The larger Rios were reported as "burning up" and thus leaking toxins into the water, but the smaller rios, like the 50 and 90 series werent reported as doing so.
From my limited experience, the smaller rios only have a problem of restarting if you unplug them, even if they are clean.
Personally, if I have a tank of coral I would not take the chance of using a larger RIO, since the difference in price of a RIO compared to say a maxiJet is negligbel. I use a couple 50 series RIOS in my tanks, and the only problem I have with them is restarting after pulling their cords. I have one 50 series Rio in my clowns nano tank that was 95% out of the water all night and sucking air, but in the morning when I unplugged it, and refilled the tank and plugged it back in it was still pumping and had not burned out.
It has something to do with the RIO's getting too hot and the epoxy surrounding the motor getting too hot and melting and polluting the tank.
I have also read about RIO's shocking people, so a ground probe in a tank with a larger rio (say 1100 or larger) might be in order just in case.