From all the product reviews I have seen on the RC-3 and RC-4's I would have to say the RC-4.
I am not a knife expert, but from what I have seen the RC-4 should do the trick.
As far as ticks, the RC-4 should work good in cutting them in half to kill them after you have picked them off your body

, so in a way it is good for tick defense as well
The Nessmuk book had a recipe for a good anti-bug rub you put on to keep EVERYTHING off of you in the woods. I don't want to get off topic here but if I find a good section for that recipe I will post it in this forum.