Leicaflex SL: slightly more camera than tank....
You would get:
Better mirror damping
Better shutter damping
A far better viewfinder (probably the best SLR viewfinder ever - sorry Olympus OM fans... )
In some/many cases, better lenses.
As I said, maybe less of a tank than a Nikon F2 (do tanks take good pictures?), but a Leicaflex SL has famously survived being ejected from a crashing fighter jet and lying on the desert floor for months before being found.
Whatever you decide, newer *isn't* always better, often just more cheaply made....