So after playing Marc with his repeater crossbows and being a sometime Lizardmen general, I decided to run an analysis on the benefits of the 2X multi-shot. The summary is this: For dark elves it is rarely worse, and often better to shoot multiple shots. The lower your to hit score, the greater the benefit. With a 3+ to hit going multi gives you 50% more hits on average. With a 4+ this drops to +33% At 5+ and 6+ they are the same. Although with more dice you have a greater chance of an average result. So the only time that it would make sense to shoot single is when you need a less likely outcome. Like if you have three shots that all need to wound to win the game (last turn maybe) you would be better off trying to roll three sixes of three dice than you would three sixes on six dice followed by three 4+s.
With Skinks this axiom no longer holds due to the inclusion of the poison rule. The skinks should always go multiple to try and get more possible sixes and therefore autowounds until the point where the multi shot reaches 7+ which cancels poison. This tips the balance to make multi shot much worse.
