You might want to check Alloy Artifacts website. They may have some info.
What I have read is they were claiming the 7/16" drive size in the steel they were using was strong enough to be used in typical 1/2" drive applications. And it was plenty big enough to replace 3/8" drive, too. But I don't think it took off like they wanted.
First of all, all of your existing sockets would be worthless - you'd have to buy their proprietary 7/16" drive sockets. And I don't think mechanics were thrilled with that prospect.
Some ideas stick, some don't. Just how tools go.