I own a Dell Venue 8 Pro windows tablet but I must say, since owning a 1520, I rarely if at all use my tablet. I feel there is no need. It's just more convenient to get out/use the phone.
I would consider going phone only if IE on WP functioned the same as Modern IE. The 1520 in landscape is pretty good for viewing full websites. I even have my setting to display the desktop view. However, it's just not as good when it comes to interacting with sites. Using the web is simply faster on my Toshiba Encore 2. And while my Toshiba is only 8 inches, those extra 2 inches make a huge difference.