Have never used the Dyneema rope on a winch, but I have used dynamic climbing ropes a lot when doing roping in the Army.

One of the major drawbacks with synthetic ropes is dirt and in particular sand. Once you have this stuff in between the strands of the synthetic rope it's life is significantly reduced. The stretching, pulling and twisting cuts the smaller fibres in the rope, reducing it's strength and safety.

Dallan Tha Bossman wrote:

...however as a popular mythbusters episode showed where they purposely tried to reproduce the myth of a broken wire under extreme tension cutting someone in half, they couldnt do it. The pig they used never even had the outer skin cut... bruised yes, but lethal? Not in their tests (and imo, they did a good job with this one).

I remember seeing that episode Dallan, and as you say, they did their best to produce a result. Pig skin is significantly tougher than human skin, especially after it's been hung in a cool room for a few days...so I think that the result of their testing was flawed for that reason. Had they used something with an "outer coating" that more approximated people skin I think we might well have seen a very different result. I don't think they would have cut anything in half though.

I have seen the end result of steel cables snapping and hitting trees etc, and there is no way I would want one hitting me...bruises would be the least problem. Even a synthetic rope would do nasty things to a man...look at the damage a whip does.

Regardless if the pig is decapitated or not, or the operator is decapitated or not, I sincerely would not risk this.
Either way, it will hurt a hell of a lot and it will ruin my day if it does happen.
In the past whenever I use winch, I drape a ground tarp on the wire anyway.
It will act as a big sail to slow down the whipping.

As long as you replace it at the first sign of wear or rust it shouldn't snap.
Well, unless you put double the rated load on it.

having been in the bush watching a D7,HD6,HD11, and many other bullys winching out logs and having hauled 6 chain of 1 1/4" rope down to hook on in mud and shite 15kgs sounds like a breeze!!!! it is amazing the stretch a length of wire rope has the logs would go up in bounds while the winch drum steadyily rotated. I have seen that wire snap/fray whiplash around and sure as heck wouldnt like to be in the way. much bigger than the 1/4"???? size you will be dealing with. only good advice I could add would be to get a layer? to spool the rope evenly if you can like they have on good salmon reels to lay the coils neatly. or just make sure you spool it on right as soon as you out of the dodoos as has been said trying to untangle it is no picnic.