I'm sure manufacturers tweak their recipes, but I do believe there are "better" salts.
I know on most of the Triton results IO/RC/AS/Seachem, and I want to say a couple others have routinely tested high for lithium.(goes from a few hundred times higher than NSW to a few thousand in a couple salts)
I've had some people say 'oh it doesn't matter, I'm not breeding anything!'
But would my Black Sun Coral have had larval settlement if my Lithium was higher?(along with some tunicates, sponges, and other forms of life) It would make a good experiment, but I'll leave that to someone else to try.
Trying to find the link to the actual research, but here's the gist of it.
In the late nineteenth century, Herbst discovered that the lithium ion has powerful morphogenetic effects on developing sea urchin eggs [3]. Since then, lithium has been proven to cause morphological deviations in representatives of almost the entire animal kingdom, but seems most dramatic in primitive embryological systems. Deviations ranging from exogastrulation to cyclopia (development of one-eyed monsters) have been observed in tunicates, cyclostomes, teleosts, cephalopods, and many other organisms. These effects are believed to be a result of the lithium ions ability to interfere with metabolic processes that are responsible for the determination and differentiation of a developing embryo.
http://www.enclabs.com/lithium.html
Also some background
https://www.google.com/?gws_rd=ssl#q=lithium+developing+urchin+embryo