That sounds reasonable. I just honestly didn't see a reason for the 3rd drive since most of the time you won't need that. You can create a system image of your OS in case something happens, store it somewhere else. File backup can be managed many different ways as well.
The only time I "really need" the RAM is Corel Painter 12. It seizes the max amount you allow it to (in preferences) and won't let go until you close the program.
For example, if you tell it that it can utilize 50% of your available RAM on your system of 16GB, it will take 8 and not let go until the program is closed.
Since I do a lot of multi-tasking it's why I just maxed out the amount of RAM I could put in the system.