There's some commentary that the Ultra 2s on the Wyrm aren't really about damage. Granted, I fueled some of that, and in a modern setting (espceally an early Dark Age setting, with mechs being very very rare and tanks and other irregular things abundant) I do think that has validity.
But, one of the lovely (and terrible) things to note about the Wyrm is that the Ultra 2s make up about half it's ranged damage. They average about 6 damage a turn. So do the LRMs. Since the AC2s have more range, they'll actually tend to be more than half the mech's ranged damage (until they jam). So, if using the mech to actually try and damage foes, they're probably the correct choice.
That said, for luring some fool into the welcoming embrace of a Hunchback IIC (or comparable; Kodiak? Turkina D? might even work in a BV game since the Wyrm is so terribly cheap), I'm honestly not sure which class 2 AC is best. But, I am now determined to try something like that some day.