ADU permit or not; financial implications

[Saika Maeda]

Hi all, 
I'm almost in escrow with this single family home in LA with an un-permitted large ADU with a Certificate of occupancy. An architect told me that even though ADUs should not be bigger than 50% of the main house, I should be able to permit this one with SB09 if I pay a fee (about $8k according to my agent). Given there is a decent fee, I'm also considering the option of not getting the ADU permitted and just rent it as is for "roommates". I'm trying to weigh my options, and could use help to decide the best path forward.

With permit, benefits are 1) get depreciation and other tax write off benefits since it's a permitted investment purpose ADU, 2) probably better for resell value, 3) have a separate address and don't have to bother sorting out mails for our legal tenant, etc.

without permit; benefits are 1) no hassle to get the permit, 2) no permit fees, 3) no tax on rental income (as it is more like a “roommate”)

Has anyone gone through a similar situation before? Please let me know what’s the best option, or if I’m missing anything. Please let me know the financial implications. 

Thanks! 
Saika