That feature is only mentioned on the FTB wikis. The IndustrialCraft wiki pages about Industrial TNT and dynamite do not explicitly promise a 100% drop rate, so maybe that was changed somewhere along the line to use vanilla explosion mechanics instead.
Well, I guess it is a bug then. Since in single player it does give 100% drop, but moment I goes to my own server, it become 33%..
That is inconsistent with single player behaviour..