Do metal skewers make a considerable different cooking time than wooden?
Absolutely!  Metal skewers contribute to cooking the meat from the center as they pick up heat from the exposed parts and conduct it throughout.

It is a good idea not to crowd your metal skewers with pieces of food to promote this.  Not crowding the skewers also exposes more surface area for the food to caramelize.  Doing this on a wooden skewer runs the risk of burning the skewers and losing food into the grill.