I think you are underestimating the willingness of people to get the hell away from a chainsaw coming at them. And I'm sure Stolze and Tynes setting the damage so low was a result of the chainsaw being rather cumbersome as a close-combat weapon.

How about this: A character just needs a skill like "Chainsaw Maniac" or "Lumberjack from Hell" or something, IN ADDITION to their normal struggle or close combat skill. If the roll for the chainsaw attack is under that, then it does full-on, amputative firearms damage. Otherwise, the attack was just too heavy and slow to do more than nick the other guy.

Also, you might want to think about this: Chainsaws have a tendency to break when used on wood with nails in it. They're not like lightsabers, going through all other weapons -- if your opponent manages to hit the business end of the chainsaw with a lead pipe, aluminum baseball bat, or fireplace poker, it could really fuck up the path of the chain or break the chain itself, making the weapon essentially useless until someone repairs it... which is seldom done in heated combat.

I like your ideas, UV. I agree with the final point you've made; chainsaws (as well as katanas) are not godly weapons. Sure, they're powerful as hell if you use them right, but it's not like you could cut a tank in half with either (contrary to popular internet belief).

Sidebar: there's a bit of irony about this submission, considering I'm not exactly a combat oriented gamer. This came out of a brief discussion with one of my more rip-shit-up players about combat options and ideas.

Chainsaws aren't actually all that well suited to cutting flesh and bone. I was once told by a professional pathologist about a man who committed suicide with a chainsaw, by turning it on and leaning on the blade.
He did die, yes, but from a heart attack triggered by the saw's vibration. The saw didn't even cut through the outer layer of muscle.

May also wanna bring up the chainsaws nasty way of having the chain come loose (or snap) when struck. I've heard stories of those chains breaking but still having part of the chain in the engine. They whip around and lash much like a whip. People lose eyes, teeth and lots of skin to these things all the time.

Just take a look at this...
http://www.wildlandfire.com/docs/2005/chainsaw72.htm
its mild...but without safety equipment, he could have been a lot worse.

Coming to this discussion quite late in the game I cant help but agree that the +9 is a little mild in that it doesnt capture the potential of a chainsaw. The following might be a little clumbsy but i think might work.

1) On a matched success a chainsaw does firearms damage (note the damage shift is quite minor)
2) Spice to taste the clumbsiness penalty of the weapon (i'd go from 10 to 0)
3) On a matched failure the chainsaw injures its user as a hand to hand attack (Critical failure maybe doing double) This is to symbolise a broken chain or being parried into your own leg.

If you want to make chainsaws more damaging but stick with the universal simplicity of the current melee weapon damage rules, how about an additional +3 for mechanized weapons?

Wow im late to this convo. But many good points here. I agree with Grantham there^ however. Theres no need to unnecessarily complicate things.