I have an unfair advantage by having perfect pitch, so whenever I'm humming something random and it hits me like, "that would be an amazing motif", I go ahead and write it down, note for note.
Ken's method is, from what I've seen, pretty common, and it works! It's reliable, and serial muscle memory keeps those motifs in your hands for a little bit.
As for how it sounds... unless it's incidental music that will only be virtually realized, I've been taught to always write with the players in mind, as a super high priority. Unless it's an aleatoric piece, I tend to write using technological notation right away. It just keeps it in one area, which is nice.