The advantage and problem with createvehicle is that it will report across all clients in MP. That's great for artillery shells, but if you're trying to simulate massive amounts of shrapnel in a hurry, createvehicle will overload your bandwidth.
The solution we've got is to have spoofing shrapnel that gives the sound and visual effects, and camcreate the live stuff on the server and the spoofs on the clients.
We're finalizing the MP testing on the solution, and the mod (CoC_Mines) should be out very soon. When it is, we'll release with it (in the pbo) a whole bunch of scripts for shrapnel, tested, commented and documented.