Which browser is everyone using? I typically use Chrome, but I can't get the DPI fix to work for me. IE looks great, but the bookmark bar for the desktop version is too small and it isn't particularly touch friendly. I also don't see that the IE touch browser is installed.
You need to set IE as your default browser in order to use it as a Modern UI App. This is the touch IE browser.
To answer your initial question, I use Modern IE exclusively when not connecting another monitor. When connecting an additional monitor and a mouse, I use both Modern IE (on Surface) and Desktop IE/Google Chrome on the connected monitor.
As much I like Chrome. IE is the best experience for me on Surface pro tablet.
However, Metro UI IE suffer page reload when swipe to the right to go previous page. That is super annoying have to reload page every time. Somehow using back space is not having issue nor using desktop version of IE.
I love chrome, and kind of need it, but it makes me pull my hair out. I for the life of me can't get flash to work. I have uninstalled and reinstalled, done all of that with no help. Very frustrating to have to open certain pages in IE just to use it.