There is one advantage that 318WR has over both 7.92mm Mauser and .30'06. That is that it is not classified as a "military calibre". Therefore it is legal in those countries - such as France - where the civilian possession of arms in a military calbre (no matter how obsolete) is prohibited.

Despite the fact that 7.92mm Mauser went into the history books as a military calibre in 1945 (excepting the BESA) and .303" and .30'06 in the 1950s in France these are still prohibited.

Indeed in France where .308 Winchester is prohibited the 7mm-08 is its most popular lawful substitute.

However as a non-military replacement for 7.92mm Mauser or .30'06 I would believe that the "wildcat" 8mm'06 would be better than the .318WR.