Overated? The 7mm rem mag is over 300 fps faster than a .270 with a 150 grain bullet. Real advantages come into play with loading the 7mm rem mag. Velocities over 3200 fps are easily achieved.
Also to the original poster, if you are considering a custom build rifle and you dont plan on much stalking then go with a larger cal. and have the rifle built on the heavy side to reduce felt recoil. Maby go with a .338 win mag and a 10+ lb rifle for example.