An important thing to keep in mind about all MathHammer is to make sure you keep the context in mind. Just because something is better at destroying a unit and has more potential damage/points does not mean it is the better choice. For example, taking a helldrake with the autocannon may be better against flyers, but if the enemy has one flyer and a bunch of infantry then it would be much better to take the baleflamer. Also, it may not be best to take any dedicated anti-air at all because it would take away points for something that is more important. Just remember that figuring out probabilities can be very helpful, but you need to test out your lists and determine the weaknesses and strengths.
Aegis Defense Weapons
This one is a little more straightforward. Which is best, Quad-gun or Icarus lascannon? According to this, the quad gun is much better in terms of getting glancing hits to strip hull points and surprisingly, it is almost twice as likely to get a lucky roll on the damage chart to explode the flyer! The Icarus would come out on top if you were using the weapon against a land raider since the quad gun can't even dent it, but other than that the quad gun wins!