I do a 50yd zero on non-magnified optics and irons.

This has been a great discussion, and it's very academic, but the reality is that your zero should be based on your terrain, targets, and how well you/your ammo/your rifle shoot.  We tend to forget about that last part a little bit.  

Can you estimate your range accurately enough to figure out your hold over/under?  Are you a capable enough marksman to estimate the target size in relation to reticle enough to place your hold over/under?  For me, that's one reason I like the 50.  It's a little more forgiving to the shooter, and you have to think about less stuff while you're busy dealing with the zombie hordes/incompetent range bros/Fudd RSOs.

This is a great target to have when trying to see how your zero works at different ranges. Pic was take from Molon’s AR15 Zeros and Trajectories post.

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Same here