@Ostaff said in Hitboxes depending on size of player characters ?:
Ostaff is sneakly invis walking across the bridge over the large vale, he closes in on his prey. He takes this time to give thanks to the Gods that be and....
right before he makes his stab, Leroy Jenkins comes running down the bridge knocking poor Ostaff OFF the bridge into the big vat below!!! ARRRRRGGG!!!! Spoiled again!!!!
Point of the story.. don't take too much of your time to think.
Also, pay attention to your surroundings, and you may notice Leroy coming your way, way before he can ruin your plans. 
I also agree with Kralith, using collision mechanics, everything should be caluclated from the aspect of characters view/position. It only makes sense like that.
TBH, I am totally for collision mechanics, if it will be possible to implement it properly, because it adds an extra layer of tactics to gameplay, which can only be a good thing. And it also partly helps against fighting the zergs. It would definitely be harder to fight them without collision mechanics.
About potential griefing using collison mechanics (what we have clearly seen in many games, for example, ArcheAge, cart blocking)... just add a popular "sneak mechanic", where when you activate "sneak mode" you turn off colision mechanics for yourself, but your movement speed gets reduced. So if you are collision "griefed" on your home door, for example, or anywhere else, just activate sneak mode, pass through.
Speed reduction is there so people can't exploit "no collision" in combat, it's a penalty that makes sure, when your collision is "off", you get another disadvantage to balance for that.
It could potentially even make another layer of strategy planning in combat...