Granted it would be a mistake to elevate this above the task of actually getting the job done, but I see no shame in promoting OSS as a matter of policy provided there are no overriding practical considerations.
My point exactly. Anyone making recommendations with any sort of bias blinders on, whether is be (corruption) getting paid off by a corporate entity or personal agenda (being an OSS zealot), is inherently not to be trusted. Getting the job done is the key. In the best way, for the least money, and serving the public good. The OP suggested that he wanted to convince the powers that be that OSS was the way. The absense of any other reasoning suggests that he may have a personal agenda that is clouding his judgement. It is not and should not be OSS vs. Commercial software. It should be solution A vs solution B. With all the aspects of those solutions taken into consideration. If solution B is OSS, perhaps it gets a +1. But OSS is merely one of the factors, not all of them.
You will have many recoverable tape errors.