Apart from the statistics, there is another important consideration on the twin/single debate; the psychological factor. It's all very well being aware of arguments for similar stats on accident rates, but what about the levels of pilot stress and anxiety, particularly flying single engine at night for example? Regulations and statistics apart, I know what I'm more relaxed in, and that is likely to make for better decision making. And of course pax are going to even more affected by the relative levels of confidence of 1 or 2 engines, assuming they actually know what they're flying in and understand the difference - which they often don't!