As a former owner of a .257 Roberts, If you are going to handload, buy the gun. If not, don't.
The factory ammo for the .257 just isn't very good. You have a very limited selection of bullets and weights. It also isn't loaded even close to the max.
My ruger was very accurate, but I also found that on larger northern deer, and at yardage of 200 or more the factory .257 just didn't cut it and although shot placement was good it didn't "drop'em" making for some very difficult tracking. Handloads did help, but my confidence in the gun was no longer there.
I would look more closely at 25.06 or .260 rem. Both have better bullet weight/selection. However if it is the 722 that you are interested in, then caliber should not make that much of a difference.