As mentioned in another thread, thankfully I have never experienced one of these props exploding but I witnessed this happening twice on a friends airplane. The engine was one of the original YS 120's and on the first occasion, the prop exploded and the whole engine was ejected from the plane. He made a very nice landing without the engine which was quite amazing to me considering the CG location w/o and engine. About a year later, he experienced the same thing again and this time, the engine separated into two pieces with the back half remained with the airplane and the front half was ejected into a field never to be seen again! Another good landing and the plane finished its life quite happy with a 2 stroke Webra 120 and wood props! Unmodified these props can have issues so why modify them and risk even greater issues. I'm sure they have their place on some planes but not on high performance engines or in a modified form.