I am naturally drawn to a paper thin road racing shoe like streak or mayfly because they feel great.
But lately I hear the vapor fly might be faster even for a mile. Now I have not worn it, but I can't imagine running 4:20 pace in alpha fly, but the marathon record is not much slower than that, so maybe it is okay.
Any of you watch any elite road miles lately? The top guys normally has a good feel for what is fastest.