which rounds for smooth feel and piano clarity?

Remember that pianos get their clarity and attack from being struck by a small, felt covered, mallet.

Replicating that is impossible without light slapping.
 
totally. Its a figurative speech. Piano like clarity just meaning a string that has a strong fundamental and lower harmonic overtones, as well as a clear top. Basically a string to balance out a big and somewhat furry mid/low mid.

And yes.. Im aware of how pianos work :)