Both are great guns. Hattles makes a good point. The Vinci has an "inline inertia" system. Some may say it shoots faster because the return spring doesnt travel as far. I would say go on comfort. If you can shoot them both, definitely take advantage of that. At the very least, shoulder them. For fitting purposes, I usually shoulder the gun with my eyes closed, and then open my eyes to see if I'm looking down the rib or the side of the barrel. This doesnt work for some people but it gives me a good idea of how everything lines up. You will have a great gun either way, just go with what is comfortable.