That is not quite right, DaGr81.

I think (although i could be wrong) that dplay_localfunction works just like calling proc_local once in the entity function.
proc_client is not needed then, as proc_local already starts that function on all clients. also, dplay_localfunction does not affect the server, as you wrote.
and btw, you should never use proc_local more than once on one entity.

now to the downside of dplay_localfunction:

when its enabled and an entity is created with ent_create, the id (aka handle) of its function has to be transfered. Thats a bit more traffic, but its worth it if you need some code running for it on the client, as you'd have to use proc_local anyway.
But if you do quite a lot of ent_creates for entities that don't need a local function running, you'd waste some bandwith, and you should turn off dplay_localfunction and use proc_local only for those who need it instead.

I'm not 100% sure if the above is true, but its very likely. only jcl could confirm it.