Having a print shop will definitely bring a lot of advantages like reduction of processing cost as you explained and having a product specification that meets your test with timely delivery as at when needed.
Another thing to also consider is the cost of maintenance and availability of power plus cost of processing with respect to energy consumption. These challenges I think are common to every business.
But on a general note, I think if the printing shop is well managed it'll be more advantageous generally.
Great job with the team 👍