I know the cloning devices sound great, and I agree they are the way go to.  
However, from a developer POV, I now need to:

 Try /dev/bpf if it exists.

 Try /dev/bpf# if not.

Why didn't we just make /dev/bpf0 the clonable device, and remove all other 
numbered devices?  This would make no changes in applications that 
try /dev/bpf0 first -- they would simply succeed.

--Michael