Shorter cartridges exemplified by the .284 and .308 Winchester families tend to be a little better. Short powder columns result inmore uniform ignition. In addition, short actions tend to be stiffer, which also helps accuracy. This may also be true of the short-short magnums such as the WSMs and the SAUMs. I have no experience with these yet, so cannot say for sure about them.
Agreed..
If your hunting I am not sure the slight difference between long and short cartridges would be of any concern. Comp shooting would be a different story..