YouTube Content I.D.

[DWMusic]

Recently, a production library offered me an addendum to a non-exclusive agreement. asking to be designated as the exclusive digital distribution rights administrator for my signed compositions.
This would authorize the library to collect the advertising revenue from the YouTube Content ID system and take a %15 admin fee before paying my artist share.

I currently don't have any tracks in the Content ID system.

My question is:

Is the %15 admin fee reasonable?
Is it better to allow the libraries to register the Content ID since their clients are using the tracks?

and

Am I better off registering all of my tracks independently to the Youtube Content I.D system?