I use the close bomb to catch runners/dashes etc. Since people react to the startup of Smoke Bomb you can just react to their dash/run/slide/whatever with back. It's pretty good. As for far smoke bomb, in theory it would catch backdashes if somebody tries to backdash out of your plus frames. I think there's a thread showcasing that EX far smoke bomb can be like +14 or something, check it out.
EDIT: When I say backdash out of plus frames I don't just mean like backdash when your slightly plus. I also mean like if you do B1~Ex Smoke Bomb and they block but try to backdash - you could use far bomb to catch them backdashing.