Toby,
In my 31 years of reloading the only rouns that I crimp are magnum pistols and autos. I can see where it MIGHT be necessary to crimp magnum rifle rounds or ammo for tubular magazines. My feelings on the topic of crimp are that it adds one more variable to your reloads - unless you have some secret way to make sure that each crimp has the same overall tension on the bullet when combined with the neck tension that is already there. I don' t see bench-resters crimping their rounds and if it was a big advantage they are the first to use it. I have never experienced bullets moving in the case necks in any of my weapons.

Reloading is about experimenting (within the limits of safety) so try it and see if it works for you.

PaulS