Your question is about Certification, not the implementation of a Quality Management System (based on ISO 9001) isn't it? I want to be sure, the correct question is answered...
Certification benefits don't affect many things people have posted about, since that's more about having an effective management system and implementation, not what your CB brings to the table!
So, if you truly are asking about the before and after of certification, I'd expect something along the lines of:-
An increase in opportunities to bid on work from new customers (they chose you because you have a certificate)!
A reduction in disruption/costs associated with customer audits. (some won't need to audit you if you have a certificate)
A reduction in time taken to complete customer quality surveys (don't complete the form, just send a copy of your certificate)
What value do you attribute to the findings from your CB auditor? (you pay them to come in and find something, don't you?)