Later series Rallyes with the taller fin and rudder (100S, 100ST and their 150hp bretheren) were intentionally spinnable but have to be thrown in otherwise it is prone to a spiral dive.
The 150ST was supposedly aerobatic in the 'utility' category with reduced fuel and payload. Have been through a couple of loops many years ago in one and found them basically simple with no vices. Its lack of inverted systems and overall puff would tend to leave it out of the aerobatic competition arena.
If flying one that has been previously aerobatted look for ripples in the upper skin of the wings as this is where the tell tale signs of high G manifests itself.
