I'd have to disagree with this. I have boots with both rounded and boxed toes. They work great with both. I always hear the opposites of these arguments. One guy couldn't get it to work with the rounded toe but can with the boxed, the next guy can't get it to work with the boxed but can with the rounded. The new split cap is pretty decent.
The recommendation to buy a more boxed toe boot came from Union to me in a PM.
I've got nothing against Union... outside of the toe strap they're my favorite bindings I've owned and rode. I rode my Cartel's last weekend and spent the whole time wishing I was on the Sl's. I've actually decided to keep the bindings and go frankenbindings.
Everyone can keep defending the toe strap but we don't see as many threads with people having issues with other companies toe strap.