Right
1) The heavy weight plastic that more of these are made from has zinc added to it to make it more metal like. This means it is also quite brittle, and does tend to break after heavy useage. This is less so on revolvers, as nothing moves when the cap goes off Replacement parts can be bought, but are expensive and not readily available.
2) the caps are illegal in HK, and I've heard it's difficult to get hold of them in the US.
PFC revolvers have no recoil. Most modelguns have muzzle flash and all produce smoke/sparks. However, the metal kokusai revolvers have a blocked barrel