I am trying to determine whether a managed or unmanaged gigabit switch is better for NDI.

It also depends on your organizational needs. Bigger companies may have security, resource control and traffic segmentation needs which would require managed networking hardware with larger bandwidth and smaller companies may not need anything more than decent unmanaged gigabit switch or two. It does make sense to look at any future growth and buy into that .... it will save you money down the road especially if you think we're heading towards some inflation of the economy.... cheers