Maybe spending the extra now with all the upgrades (including the water cooled option) is ultimately better for me since what I want to avoid is any problems (hence my concern with overheating etc.).

What charger do you use for the two 8 cell batteries? When I was looking at two 6 cell batteries I was eyeing the dual charger but it doesn't work for more than two 6 cells.

I'm starting to see an extreme in my future.