I don't honestly think that you're less likely to get in trouble because you stab rather than slash someone. Sorry if I went overboard in paraphrasing, but is that seriously what you were saying strambo??
Basically...but not that simple, it's just a point to ponder.
First, we are talking about a deadly force scenario, you should be doing whatever will best help you survive. I feel penetration is better than slashing based on anatomy and ancidotal ER evidence as well as historical evidence from when warfare was edged weapon dominant.
I have a photo that made the rounds of someone sliced deep all over his body. He's carved up like a side of beef. He killed the person who did it to him. So, I advocate using penetration for rapid incapacitaion as a survival tool.
As to the legalese (which only matters if you survive). Re-read Zoogster's post. The police are pre-disposed to see any knife event as being either a murder or at best mutual combat, not pure SD with the knife user being the good guy.
Anything that adds further evidence to this notion would be bad. As far as wound patterns: with a blade up grip, yes, the cut would be to either the inside or outside of the forearm and probably biased towards the top. However, with a down grip, the blade is used to trap as well as cut and the slash would be to the inside/outside and towards the bottom.
Hold you forearms up like a shield and think of someone slashing at your throat. You will get cut on the bottom, outside and inside of your forearms as they slash from side to side.
Add in the fact that the threat will switch from offense (after you "de-fang" his weapon) to defense...and he will get some classic "defensive wounds" as he tries to shield from your further slashing attacks.
When the dust settles, you are left with (lets assume for this case) dead attacker, his wound patterns and your word. If there are witnesses...hope they are good ones.
It may be a minor thing: having to deal with the criminal justice system after killing someone w/ a knife is gonna be
bad either way. I would rather have to explain a small penetrating would to the heart, aorta and/or kidneys etc. (the knife equivalent of shooting) than all the cuts to his arms and why he was still the aggressor in spite of them.
That said: the legal battle comes after, I will use what I think is most effective to stay alive and deal with the aftermath. I don't think slashing is nearly as effective as penetration to certain anatomical areas. Either way it is going to be an ugly mess during the fight and in the courtroom.
Oh, I have a couple CS knives...there is some really good value in some of them like my Recon Tanto, small neck knife, and cheap (but rugged) folder I got in the PX for $30.