Upgrade only if you need more screen real estate for mutli-tasking, editing programs etc. But for gaming I personally don't see a difference. PLUS, you need a stronger card to keep up with getting the max settings for your 1440p resolution.
If you primarily are a gamer then upgrade to a 120hz/144hz monitor at 1080p or higher. You'll notice the difference more and to me it is SIGNIFICANT, especially for FPS type of games.