aero socks depend a lot on the person wearing them and their pedaling style, and likely how vertical your lower leg stays. Trip socks are the hardest to nail down, because you also have an element of user error when putting them on.
I tested a few pair a while back... trip socks were best (although the rule28's and their clones weren't out yet. Part of the premise behind them is that they remove the human factor and possibility of screwing it up) for me... and it was more than outside the margin of error. However, that's n=1... Wiggins wore trip socks for his hour and no socks for team pursuit... so take from that what you will. A fellow on ST tested shoes, a boa dial "chunky" tri shoe vs. super slick Team GB approved custom Simmons shoes and found almost no difference, yet others found large gains going from boa shoes to lace ups. (again, I imagine a lot of that depends on how flat your foot is through the pedalstroke)
Like everything to do with aerodynamics if you don't test you are really just guessing... you can make educated guesses, but no promises if it worked for 99 people out of 100 that it'll work for you.
*Funny thing I heard, Jim Manton (from Erosports) helped the US Women's Pursuit team for Rio... they tested a LOT of socks. The best ones they found? The socks that Assos had given them to train in. (Not the socks Assos planned as aero socks) The problem was nobody at Assos had kept that "recipe" around, so the women ended up using those stark white socks because that's all they had.
I agree though, the safe/cost effective solution is shaved legs and hidden socks.