I don't think there is any difference in chances of getting sucked in with the stream rock vs. mounted on glass. If anything I would say it has a slightly higher chance because my RBTA always prefered to stay on the rockwork vs. the glass.
I had a RBTA in the 125g with the streams. RBTAs like to snuggle there foot down into rock and it was on the move could very well think the hollow of the stream rock may be attractive. The suction is pretty good under the rock and could definately do some serious damage it is did move.
The 125g setup was pretty short lived and only lasted 3 months but it was a very big concern. However it really did like the gentle current the tunze on the opposite end provided by the time the current reached about 5' across and didn't move much during that time.....
The suction was enough that a
Hippo tangs liked to get under that rock and when the timer came on for the pump it was powerful enough that the tang couldn't get unstuck from the intake. I did learn quick though......
I personally would only recommend streams on a SPS dominant tank where high current is a key factor or a non-anemone tank.....
