I got mine years ago for the ammo deals at Century International Arms. Now I understand no FFL is needed to buy ammo from them, you just won’t get the discount prices a FFL can get it for.
CLEO signature is just that. You promise to mail a copy of the application to your CLEO for him/her to sign. This is an acknowledgement to your CLEO that you have applied for a C&R FFL.
If you mail it you won't know whether your CLEO signs it or not. It doesn't matter anyway. The BATF makes you promise that you will mail a copy to your CLEO and has no affect on your approval/disaproval.
The biggest con is your forfeiture of the 4th amendment. For me the way I see it is that it doesn't exist anyway. If they want you they will get you.
For those unfamiliar with the 4th here it is.
Amendment IV
The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.