I also wrote an article discussing why "Committed Use Discounts" is a much bigger deal than just a "price model" at [1].
It'd be great for "thefht" guy to do the comparison, but data's already out there.
(work at Google Cloud)
[0] http://www.rightscale.com/blog/cloud-cost-analysis/aws-reser...
[1] https://hackernoon.com/why-googles-answer-to-aws-reseved-ins...