Xio,
Unless you are making finished devices, you don't need to pursue any medical device standard(ISO 13485). I would encourage you to improve your response to customer needs by providing specific services to companies who make medical devices and be knowledgeable about them before they ask...understand:
What it means to qualify a mold for medical devices
What it means to do Installation Qualification, Operational Qualification and Performance Qualification.
If the customer is within FDA regulatory requirements, then they are suppose to have quality requirements for you that are spelled out in a supplier agreement and somehow managed to assure that the requirements are being met.
You are creating more work for your company if you intend to move to 13485 as that will create more burden on your processes that may not affect medical device companies. You could attempt to have both certifications(9001 and 13485) and have a hybrid approach to taking care of customers, but I think this is more work than is worth it.
I don't see having ISO 13485 as an asset. Knowledge about your customers needs is an asset. Spend the money to send some people to medical device seminar on process qualification or similar topics.
Is having 13485 create additional regulatory burden? NO. Unless you are making finished devices, there is no regulatory requirement for you. Only your customer has that burden, but they may pass on some of their requirements to you, ie, agreed to within the supplier agreement.