It would be better if it were all bike traffic. But bike traffic can be stressful too. You will always have people who just don't know about trail etiquette. People who stand and have a conversation in the middle of the path, on a blind curve. People who ride two abreast and hold up traffic. People who sneak up on you and don't know enough to say "on your left." People who ride with their dog on a long leash to their left. Little children, God bless 'em, who swerve unpredictably all over the path. Adults, God damn them, who do the same. These are some of the reasons that I doubt it when you say you can ride as fast on the path as you can on the street, unless you have some enforcement of these cyclist infractions, or effective education.

Also, I'm just saying that there isn't anyplace that's stress-free. The streets and the paths, even the MTB trails--all have their own aggravations. If you're an enthusiastic and open-minded rider, you can still have a lot of fun, even though the stress level is greater than zero.