Wow, that makes me so much more excited for WP8.1! I'm always finding myself irritated with the current Mobile IE. It lacks so much in functionality. It doesn't know to go back once you go to some app and come back, you only had one button and that was either tabs, refresh, or favorites. And with the Lumia 1520, most websites rendered as if the screen was much smaller.
I just checked to see how WP8.1 handles phablets, there is now an emulator for a 6-inch 1080p device. The whole OS now handles phablets pretty damn well. Appbars aren't huge any longer. In fact, if you are using an app with old code, you don't get a huge appbar, instead WP8.1 compensates by making it the same size but puts a black bar underneath it. It is so nice knowing IE11 won't look so damn useless on my Lumia 1520, or how every single app I have looks comically sized on my phone.
Oh and also during my testing, even if we didn't have this swipe back and forward gesture, we at least have a functional back button now! I tried browsing the Internet, then opened up Messaging, pressed start and went back to IE, and then pressed back and instead of taking me back to start, it took me back to the last webpage.
I can't wait to have this on my phone! This is so exciting!