Double technical don't countdown. It is a Double technical when it is destroyed at the same time as a technical message. If a technical message is displayed but it is not destroyed, it is undead technical.
My first impression as well, but they're played quite differently! Strikers don't have melee attacks whereas Gunbird 2 is more aggressive and rewards getting close and personal. That alone changes the gameplay and level design a lot. It's not that obvious with Tavia because her main shot is so powerful that it doesn't require getting close too often, but check other characters :)