I like the cable guides on top, continuous housing because it 1) you can pick the bike up by the top tube and not ever have to think about the cables and paint and 2) minimizes housing openings and rust and 3) adds some compression to the rear brake housing, making less effective relative to the front and making the braking front and rear more uniform.

I never sweated enough for sweat on the top tube to be an issue. (I also ate a low salt diet in my racing days and have tried to keep my salt down since. Means my sweat has never been exceptionally salty. I did it to stay away from sodium depletion issues on hot days but it had other benefits too.)

Ben