Hi Jamie, 40 is 268mm and 41 is 276mm. Keep in mind that Scarpa uses what they call the "optimized touring point" which can effectively shorten the length depending on the fitting placement on their boots. On the Alien 3.0 it is -5mm from a traditional fitting placement.
Hi Alex, the Pika is a great binding and I think you'd be very happy with it. It does not have a hole pattern that corresponds with your specific Dynafit bindings and you'll have to drill new holes if you want to use it.