Been on narrow (20-22in) bars for almost 15 years now. Every few years I try out wider bars and keep coming back to what I know. Couple of weeks ago I setup my townie with 685/27" bars and they're just too wide for the city.

If your bars are wider than a Citibike's, no way you're gonna be shredding through traffic.

Outside of a city riding? Go nuts! The actual comfort factor with 27" bars is fine. A little better climbing, a little more like driving a truck.