what is the big deal with head stamp...I've been shooting mixed headstamps for over 30 years with no problems
I think the main intent here was to make sure there are no crimped primers.
This way it save the hassle of swagging them.
On Rifles if you shoot for precision different head stamp will give you different brass on the same "settings" some brass will stretch more or less have thicker or thinner walls etc.. Running Mix HS on the same die without adjusting will yield different brass specs.
Now comes the question will a mix HS brass will shoot with no issue and the answer is yes, it should. The variance in the loaded ammo should still make it shootable as long as it is still in sammi specs.
Will you be able to make grouping of bullet on the target as good as "precision" brass? probably not.
Are you a good enough shooter to see the difference?
Does it matter?
Do you shoot hair pins at 200yrd? or shooting soda cans in your back yard?
I think all of the above questions are answered differently by different shooter with different needs and therefor it is all about preferences.
My 2 cents