Worst for me personally was 6 months back using the 661 limbing a large pine I'd dropped, the 661 caught a smaller branch piece and flung it into my knee at high speed..stopped me for the day and left a limp and large bruise for a few days..my god it threw it at my knee fast. Otherwise worst cut thank god is when hand filing and even brushing the chain after sharpening results in a nice wee laceration.
But at work have attended many chainsaw accidents, ranging from facial cuts we have to suture in the field before transporting to hospital, otherwise the pt would bleed to death, down to the plain old nasty cuts in shoulders/legs which are very messy and ragged, usually leaving a 1/4 to 1/2 inch horrible wound.
I think in all honesty people need to personally see a decent chainsaw cut to appreciate how much damage they actually do... and the deficit they often leave behind such as loss of movement of limb etc until surgery has done its magic. And if you happen to get an artery in the arm/groin, its a life or death situation.
For me I stop the second I start to feel tired or hungry/thirst and rest, as I feel this IS the time an accident will happen. And I now grab the smaller saws as soon as I can, no more limbing with the 661 or 440 when the little Shinny 352 will do it...the lighter weight reduces fatigue. Sure the 661 with a 20 inch bar will limb like a psycho and save time, but it would also limb a lower human limb half off in a millisecond..so I just don't do it anymore..to me its a risk just not worth taking.
Watching homeowners use saws scares me, seeing the one handed use, flinging the saw round after each cut when the chain is probably still doing 40mph...and the blunt chains which are dangerous in themselves..and of course no PPE..over here we have a real "she'll be right mate" attitude which often bites them.
Take care out there guys, as a devastating event could be just around the corner, keep safe.