I've cut my bars from somewhere around 60cm down to 38cm (almost the width of my hips).
Let me ask you this: do you ever think whether your body will fit through a gap while walking? Do you ever wonder where any part of your body is, while walking? I know I don't.
As you and I perceive our bodies, I perceive my bike. It now feels like an extension of my body.
I can now ride through a crowd of people, shoulder to shoulder, and they won't notice that I'm on a bike. I can filter traffic like I never thought was possible (HOW I LOVE THIS!!) and I can get around obstacles more easily. Everything feels natural!
And I didn't sacrifice any control, nor comfort.
Lastly, I also enjoy the looks I get on my now exotic looking bike (only the bars' length changed and the whole bike looks very different), albeit I never considered this when hacking the bars.
Oh, and considering that the narrowest gaps are those between two cars' rear-view mirrors and that my hips are higher that those mirrors, I could hack the handlebars even more and squeeze even better. (by also squeezing my legs)
I don't do it because I'd lose the comfort and possibly the control, but it could work for someone else.
To conclude it, the new riding style (discovered through the Internet and made possible by narrow bars) brought me more pride and joy and sharpened my skills more in half an year than the last 7 or 8 years of normal riding did. (I forgot when I started)
I definitely recommend doing it! (fun fact: whenever he sees me, a friend of mine insists to convince me that they aren't actually better, lol)
Cheers!