You may want to check this out
http://8wayrun.com/threads/zwei-tech-trap-discussion.8836/page-5#post-660094
Combo damage is
4B(BE), 66A+B, 66A+B = 68 - 84 (if teched)
A+G, 4B (BE) 66A+B, 66A+B = 85 - 100
B+K, 4B(BE), 66A+B, 66A+B = 89 - 107
Without second 66A+B that combos deal 56, 72 and 78 dmg respectively.
Damage gain is really nice.
For 3A(BE) techtrap overall damage would be
4B(BE), 66A+B, dash 3A(BE) = 130
A+G, 4B (BE) 66A+B, dash 3A(BE) = 147
B+K, 4B(BE), 66A+B, dash 3A(BE) = 153
So i think even against characters 66A+B is not guaranteed against its still worth going for tech trap.