I use it about 2 feet away as well, and I can tell the difference plain as day between the two. There's just no comparison. Good news for you is that if you can't see a difference you have no reason to shell out money for an upgrade! The color gamut sucks on both, anyway, so you wouldn't be gaining much.
----------
Just because something is better than all of the other awful choices doesn't make it great.
Good point at both, i see no need to upgrade, and TBH my next "tablet" will probably be a Surface Pro 2 because i still need a full "PC" for work, and can continue to carry my iPad mini with me for ad-hoc stuff