If I'm moving towards getting funding or need to sign compliance documents for the business, is there any downside to signing as my agency with a DBA vs a standalone LLC?
If you are getting funding, then you will certainly need a separate LLC. The agency will have many deals and contracts with people you have worked with, and the investors will want these to be separate from the actual product they are funding.
But it might be wise to wait until the funding is almost-confirmed before starting with this. The investors may also have specific requirements on where and how the LLC is registered, and you may need to do it over again if you do something else right now.