After a few months of usage I can say I am satisfied with the upgrade: the display of the MI5 is way better than the old one, the sensors are more precise and the overall feeling is better.
Are those improvement worth the extra bucks? My tentative answer is yes.
Also, a long overdue (hairy wrist picture) picture.



I am going to add this picture and the one from the @thebeardedwrist @TheBeardedBaby to the gallery.