Level 1 q-bomb (2 seconds) is -13 on HIT. Lol. Basically, even if you hit someone with it, you're still going to eat almost anything the opponent does on reversal. It also starts in 17 frames, same as far standing hard punch; so it's pretty slow.garjian said:ive never understood why people hate it so much... i suppose it does reduce your options while dashing... but it seems to have decent range and speed... meh.)
The other levels (hold charge for more than three seconds) knockdown, but are not hard knockdowns. It's just not worth the risk of them blocking (and being at -17) for a quick knockdown that's armour break, especially since you're giving up either your focus attack, your grab or your slide.
Tortilla or Fajita do a great job at shutting down focus attacks.