So, in other words, it's roughly a 50/50 chance for Nu to tack on an extra 3k or so damage vs Tager. That chance is a huge chance to take. If there was a way to perfect this, I could see it working, but it's simply canceled out by Tager doing a normal tech and a normal/barrier block.
I get what you're saying though. 214D causes a barrier for the Sledge to break through, whereas you then punish the Sledger with a 2C, 3C or whatever. In my personal opinion, I would still favor a knockdown > gravity well > retreat tactic. Being close to Tager for a 'maybe it'll work' chance is really not something you want to try when you're a glass cannon like Nu.
I will look into this though to see if it can be made more practical. I know I've used a full charge 214D at full range, ran along side it and either did a 2147D or a grab, or a sweep, whatever.
EDIT: I looked up dotSafety for some youtube videos, found one of you guys fighting. If you have a link to a specific case in which this strat was used, I'd like to see it