*Most* guys throw about the same from a 1KD stance as they do from a traditional stance. This can definitely be dependent on the player's arm strength, quickness, footwork, etc.

Signed catcher here, the kick/ one knee stance personally only has had positive effects on all of my defensive aspects especially blocking and throwing one of the main reasons is that it saves my legs letting me be more energetic in the field and thus letting my pitchers and infielders feed of my energy

No way to know for sure unless you try it with them...you may have some guys who catch on really quickly and are better in 1KD stances, but you also may have some guys who struggle with it. The only way to find out is to try it in practice and bullpens first.

I’m not a fan with runners on base. Ive seen one too many pass balls and bad deflections on the KD side that I believe would’ve otherwise been kept in control. I say let the kids transition if they want when they make it to the professional level and keep them developing endurance in their legs with the best defensive techniques when they’re young