You'll only find out how good it is if you try it. When you try it, it has to be your own copy that you use, otherwise some one might catch you cheating. It's only your very own copy of the new AA Summicron 50 you can master, otherwise you might risk: ruining your photos with the borrowed one, just like with any Japanese 50.
On a serious note, I really think you should buy it, with all the sacrifice this comes with.
The rest of us will enjoy the humble normal Summicrons, any generation and grab the LF camera, when the need for another kind of quality comes.