I used to think Twelve’s backdash was pretty bad. Some characters could do really useful stuff with their backdash - usually bait throws by standing really close to their opponent on their wake-up, then backdash away and punish their tech-throw attempt (Oro, shotos, etc) - but Twelve can’t do any of that with his.
But more and more, I’m finding it one of his better evasive options on the ground for two reasons. First, it has no start-up frames. Hugo is the only other character in Third Strike who has a backdash with no start-up frames but the range is poor and the recovery is looooong, which means it’s a pretty bad option for him. Necro shares a lot of similarities with Twelve (same overhead, same jump, etc) but his backdash has two frames start-up. The crucial point here is Twelve’s backdash doesn’t have any.
Second, Twelve is considered to be in air during his backdash rather than on the ground, so low pokes don’t connect like they should. So what it boils down to is Twelve’s backdash can be used to safely evade low mid-range pokes.
You may be thinking what’s the point of back-dashing when you can block or parry. The main reason that his backdash is useful, though you may find other reasons as well, is it gets Twelve away from Chun-Li’s mix-ups after she throws him.
When Chun-Li throws Twelve
Generally speaking, when Chun-Li throws someone, she’ll close the gap and get in range to go for her usual mix-up, which is kara-throw (if you’re blocking) or crouching medium kick (if you do anything else). If she kara-throws you, that resets the situation in her favour as she goes for the same mix-up again. If she crouching medium kicks you, then it’ll be followed by SAII and… well, you know what happens.
However, if you tech-roll after you’re thrown and immediately backdash with reversal timing, that whips Twelve away from the range of Chun-Li’s kara-throw AND her crouching medium kick. This effectively resets the situation in Twelve’s favour as he’s gained some distance and is now free to do what he wants without fear of getting snagged by crouching medium kick. Other characters can’t backdash out of trouble because they can get snagged during the start-up frames, the same reason it’s risky to jump away from Chun’s mix-ups.
I’m not 100% sure this technique is fool-proof as I don’t have my own version of the game to test anymore and can only go by playing people in the arcade. But since trying it out, I haven’t been caught by a single kara-throw or crouching medium kick and when you consider Chun-Li players are used to players sitting there after a throw to ‘guess’ their way out of the mix-up by blocking or tech-throwing, this viable third option gives Twelve players something to use that Chun-Li players will not be expecting.
Against Ken, sort of. Some Ken players can’t hit confirm off his crouching medium kick, so they tend to use crouching shorts instead. What this means is after they throw, they dash up and go for mix-ups that usually lead off crouching shorts or the threat of it.
After Ken’s throw, Twelve’s backdash gets him away from the crouching shorts and resets the situation in Twelve’s favour. However, Twelve can still get tagged by moves like standing MK, EX fireball, etc, so it’s not foolproof. Either way, you need to take a lot of risks against Ken to stop him gaining momentum and stomping all over Twelve and it’s always an option worth bearing in mind, especially once you get a feel for the playing style of the Ken you’re up against.
When the backdash DOESN’T work against Chun
If your timing sucks, you can still get hit when you’re inputting the backdash follwing the tech-roll.
If you’re near the corner, Twelve’s backdash becomes useless because you won’t have any room to backdash into.
If you’re on chip damage health, Chun might fire off her super after the throw, so you’re back into a forced guess on what she’s going to do.
If you’re hit by Chun’s super. In this situation, you’ll most likely be reset with fierce punch, which means you’re forced to deal with her mix-ups afterwards.
What I’d really like is someone with the game at home to test this out and see if Twelve is vulnerable immediately after the tech-roll or if it really is a get out of jail card against Chun. Like I said, I haven’t been caught out once since trying it for a month now (and this is against CIV, who’s going to SBO!) so it’ll be nice to have it confirmed just how safe or unsafe this technique really is.