I guess it depends on how you define sound and notation.

Barbara, Encore is a very user-friendly program. What I like about it for scoring is
that you can rehearse the part you want to input by playing back with the space bar what you've written without having to write it in first.

Sibelius looks better. (I wish it had that Encore feature I just mentioned).

Sibelius makes a good MIDI for export. It also can be sent through e-mail.

Mark, Sibelius is a lot more user-friendly than Finale. More done quickly with less steps.

None of these programs will produce quarter or microtones.

Jim, the intermediary MIDI step could be circumvented as you indicated. Maybe you should pursue your approach. I think that a program could be devised to accurately graph sonic information with quarter or microtones used in Asian music or traditional folk.
Charles Seeger had a melotron which graphed lines as on an oscilloscope that could
measure pitch accurately and could be read by a trained eye. Lomax attempted this
with his "Cantrametrics" (sp?) to document the world's music.

I think a program of this order would serve ethnomusicologists very well. It would be great for musicians who want to accurately analyze the styles of various folk musics.
I think that conventional notation programs are limited to conventional music notation.
They are "clunky" when it comes to interpreting the subtleties of pitch and rhythm.

Frank