Fantastic report! Great research! Thanks!
I have pretty much settled on 6" ti nails and 6" ti V-stakes due to the following: they don't bend and can be pounded in with a rock and they have "pull strings" attached to make removal easy and blood-free. uhum.
I have used both 6" and 9" aluminum nails which I really liked at first but, occasionally the epoxyed heads pop off when pounding or when trying to extract them. So, they lose points for that. And they will bend in extremely hard ground.
I have GoLite Y's and Big Agnes X's both 6" variety but the Golites have significantly larger fins. I've always believed these type stakes would hold as good or better than anything else, but, my hands are a bloody mess after extracting a set of them. Just not worth the pain.
Note however, if I know I going to be camping on beach sand, I will use the 9" aluminum nails.