Cost Center Posting on the Balance Sheet

I'm at a client that does not have New GL active. They want to use the cost center field on the balance sheet for informational purposes only. It won't be connected to CO. They are on the latest version of SAP ECC. I have done this at other clients and it worked fine. My question is if we start using the field and say a year or 2 from now they activate NEW GL, are there any implications of having these postings out there?

Any experience with this would be helpful.

Thanks,

Jim