I’ve had 2 wheelsets from Superstar, one’s actually very good, the other had really uneven spoke tension, I had it in a hybrid and it wasn’t strong enough for canal path riding. But, that’s not so bad, because it was very cheap and hte price difference was more than enough to pay for a rebuild anyway. So I treat it like a well packaged wheel kit and if it happens to be well built enough to use, that’s a bonus.
The 821’s had some stinking reviews and complaints about strength, I haven’t used em myself, they do look good on paper (my 819s were strong like ox and heavy like bus). I’m not as much of a fan of the Flow Ex as I was of the old Flow, it’s not as strong imo but it’s still great at what it does. I replaced my Flow Ex with a WTB i25 which is a wee bit heavier but very impressive- much more dent resistant than the Flow Ex.
Honestly, it’s 26, I’d be buying used as values have dropped like a stone.