We were discussing aimbots in irc yesterday, not knowing about this myself we pretty much decided that with cRPG, it would be a fairly pointless endevour to use one since my skilled ranged players would happily be able to out-do these guys.
Basically, with the fact that it is more or less impossible to have pinpoint accuracy there would still be a degree of randomness to everything that the person would do. They would have to be close enough to have their reticle to fit the enemies head perfectly or they would have to have a large trade-off on PD in order to have this.
Sure, it would be viable, sure it would be annoying to have someone with that kind of accuracy but on top of that again, the arrow speed is slow, the arrows aren't homing, you'll still be able to avoid them and it would still be as if someone was shooting at you without it.
In many ways it would be a disadvantage because although they would follow you exactly, and they would follow where you are going to be, as soon as they release the arrow, they can't change the direction of it, and because it appears to lock you into where it wants to fire, you wouldn't be able to pre-empt a quick direction change from an enemy, hitting them successfully.
Personally, at this stage of it's so called development, from watching the video, it would decrease the effectiveness of some ranged players and if there's anyone already using this, I haven't noticed, I still know which people are a good shot and which ones are not, i've not come across anyone who i've suddenly gone "omg, how the hell is he so accurate" who I haven't previously thought were good.
Personally, I wouldn't worry about it, as with the autoblocker if this ever came into the game, i'm sure it would be picked up, and secondly, i'm quite sure that there will still be people who are playing legit who are better than them.
This isn't Call of Duty where accuracy is pin point and it would be so damned easy to catch someone who had coded the game to flick around following where the arrow will be released in order to get the shot on target. (Immense character shake in order to follow where the arrow will be released, the shake would also increase rapidly because the quicker you move your mouse, the bigger the reticle would get, so you'd have people wobbling all over the place in order to shoot you perfectly and then you would instantly think "yeah, that guy ain't legit.")
Really wouldn't worry about it, honestly, I would more or less say, if you get shot, you were probably shot legit.