Maintenance and Reliability Engineers: How Are They Different, and How Many Should I Have?

So another common question that manufacturing maintenance folks ask when designing a new reliability organization is about the Maintenance Engineer (ME) and how he is different from the Reliability Engineer (RE) and how many of each they should have. We could dive into the details of the accepted responsibilities of each but I have a nine page job role comparisons that include planners, REs, and MEs that provides that detail. If you would like a copy, comment below. 
Let's look at it at a much higher level. One simplified way to think about it is an RE is focused on mean time between failure (MTBF) and an ME is focused on mean time to repair (MTTR). To say it differently the RE is focused on preventing failures from happening though statistical analysis of our history and the ME is focused on ensuring that if a repair is required it is as efficient and effective as possible so as to prevent a reoccurring failure or an excessively long  repair. Now I know we could argue the detail here but what I want is an image that we can then use to think about the number your site needs. 
Our research says that you need one maintenance or reliability engineer for every thirty five crafts persons. The question now become how mature is your site? If you have great planners and a wonderfully refined job plan library and an engrained root cause culture you may find yourself in a world where you need more REs to complete advanced analysis of your existing data in order to further reducing your maintenance cost without decreasing reliability. On the other hand if you are like many of my friends in the industry you may be a bit reactive and have only recently added a planning department, have no work order history, and don’t use the principles of precision maintenance. If this is the case for you, then you may need more ME support to get the foundation in place before you are ready to add more REs. 
This actually works quite well because many find that it is a good promotional transition to go from ME to RE to leadership roles if the engineer would like to have that promotional path. Not all engineers will want to do this but the ones that do will have that path available. 
So to provide an example: If you have 100 maintenance crafts
  • Reactive maturity staffing could be 2 MEs and 1RE
  • As you mature the staffing might transition to 1 ME and 2 REs.
In the end the Maintenance Engineer will help you get you’re the basics in place. They help populate the CMMS and develop precision job plans working with the planner. The Reliability Engineer is focusing on the future which is important to really making the change to excellence in reliability.
That's my thoughts whats yours?