This is really my problem, too, spilling powder all around. I make a full bag with a blender, and there is almost always powder going somewhere it's not supposed to.
The new bags might be easier to reseal (I haven't tried that yet) but the old ones where best to open. You could tear of the strop and then at least you only spill powder when trying to get it into the blender.
I think the ideal bag would have an opening that is much smaller so it can fill a blender or bottle without having to fold the bag onto itself.
Of course this isn't really that important, both bags are fine Just wanted to say the new bags aren't better for everybody.