It's actually a near-perfect analogy here, where actions speak louder than words re: Microsoft's commitment to maintaining adaptations of existing open source projects. I think the example provided is enough to trigger a careful analysis before jumping in, and I would love to see counter-examples to help balance the evaluation.
(Please note: very specifically requesting counter-examples of Microsoft-official, intended for production, open source repositories demonstrating long-term maintenance of tweaks of/dependencies on established open source projects that for whatever reason were never up-streamed.)