I used to stand on it, yes. I didn't jump up and down but just stood there until the mast tip came up out of the water.
I have great confidence in the Inter 20 daggers, they are quite heavy and seem very solid, I have not heard of one failing except maybe if run aground very hard, but even then I know several who have done that and their boards didn't break. The Inter 20 is a very solid boat overall, there are many that have done the Worrell/Tybee several times over.
There is nothing under built on the N20! Except for that batch of rudders they used at the Alter Cup.