For 59cm, it's always tough choose between sizes. I have lazer in size L, although some source says M could fit 5860, but not for me.
I feel lazer helmet is shallower than giro. It's better after adjust the depth fitting screw.
The top roller is easier to use than giro air lok, bigger dial better with full finger gloves.
This is my first MIPS helmet. Fortunately, I haven't had to test this safety system but I understand the rationale to deflect as much energy away from the helmet instead of absorbing all of the force to the head. Overall, I find this helmet to be very comfortable, light, great visibility, and easy to put on. I like the knob on the top of the helmet to make the fit tighter around my head...it is just easier to work with especially when I am wearing gloves. The strap also is comfortable and easily adjustable. The thing that can be weird is that the helmet sits a bit high on the head, which is accentuated since the fighting knob sits on top of the helmet verses other brands that have a ratchet system at the back of the neck that sits below the helmet. I have short hair but my wife, who has longer tied back hair, consistently had strands of her hair get caught in the yellow MIPS inner plastic plate. I can see that being very annoying and painful for some people. Overall, I am very satisfied with the purchase.