We have witnessed an ROI. It is worth the cost. 

Veeam Agent for Linux saves time, and it's worth having it for non-virtualized machines, so there's ROI from the solution.

We have not calculated yet as we just added to our existing licenses for Veeam B&R

I don't have exact numbers, but you get an ROI very quickly with this solution due to your ability to get to market very fast.