The 7 x 57 is a great classic round , but I agree with Bob that it doesn't reach it's full potential unless you handload for it...

The only advantage I can think of over the 30-06 is that it's recoil would be somewhat less with similar bullet weights...But not a WHOLE lot less, assuming equal rifle weight and stock design... Performance on game with similar bullet weights would be very similar to the 06... The 06 has the advantage with heavier bullet weights ( 180-220 grains) on game bigger than deer, but the 7 x 57 will nicely handle moose and elk out to 300-350 yards with 160 or 175 grain bullets...

If you really want a 7 x 57, go for it , but don't do it because you think you may be gaining any performance over the 30-06..