I had a friend that shot a 250 Savage for years and it is a good deer round. It is very comfortable to shoot and can be downright accurate as heck. The history behind the round is it was the first American production cartridge to eclipse 3,000fps with an 87gr projectile. Charles Newton came up with the round in the early 1900's and it was tweaked in the .250 Ackley and .250 AI (Ackley Improved) some years later to gain a bit more velocity and accommodate heavier projectiles.
You are correct that it is virtually equal to the .257 Roberts and does fall just short of the 25-06 or .25WSSM as these launch a 110gr bullet at around 3,100fps +/-...but the 250 has less recoil and noise than the larger cartridges. What you will find these days is many of manufacturers that produce the 250 will load a 117gr or 120gr bullet launched at or just below 2,800fps or a +P round that has around 2,950fps while reloaders can get 3100fps with an 85gr projectile (like the X-bullet). Because of this many feel that the round is best with 100gr or less projectiles as anything heavier (longer) reduces powder capacity and velocity.
"Shoot low boys...they're riding shetland ponies in search of true grit" Lewis Grizzard