I want to see this answered, too. This is a behavior change to a long-established feature that many of us rely upon for daily use. If we cannot rely on the order of items in a speed dial group to direct the order of the tabs opened from that speed dial group then one of the most useful features of the speed dial is lost.
At least in a bookmark group I can prepend a numerical string to force a sorting order, though I guess with the speed dial's new behavior I could not even rely on the alpha-sort to guarantee open order.