well i swiched this year myself. i went to rockey mountain snypers. (via. 5-shots recomendation)
i harvested my first deer 2 days ago and i do not think i will ever change heads again. 25 yard shot passed threw the chest, front leg, and stuck in a tree so far that i was about to give up on it when i pulled it out. it was deffinatly open on entry there was at least a 2 inch hole upon entry. so impressive i had to stop by a friends house to show him the hole. yes that is a bigger hole than the advertised cutting dia. all i can figure is as the blades slide back they actually open farther than advertized before locking into place.
5-shot could probly explain better.
i was using 100 grain steelheads although i harvested every thing i shot at i did not get the pass threws 100% of the time and it bothered me.