On a related note, does anybody run spellcasting such that opponents don't automatically know what spell is being cast when they have to use their reaction? Perhaps there could be an arcana check to know what spell it is? (Although I would like there to be some cost to the arcana check...perhaps that in doing so you consume your reaction even if you don't cast Counterspell?)
Yes, this would be a pretty serious nerf to Counterspell, but I'd be ok with that. Even when I'm on the player side of the screen, Counterspell just seems too....easy.