I would say if your going to upgrade and switch to intel you should get either the i5-4670k or the i7-4770k. the difference besides .1ghz speed is hyperthreading. Which from what I've read doesnt affect games hardly at all. It mostly depends what you play. Also, If you use vertical sync on game settings, you would stay at 60FPS or whatever your monitor refresh rate is anyway. To really answer your question though. Would you see an improvement? Sure, a little maybe. Would it be worth it? Kinda but not really. I had a Phenom II 955BE that I loved, switched mobos had problems, and then got an FX 8350 that I wasnt impressed with so switched to an i5-3570k. I'm happy and content with my system.
Intel does better in benchmarks than AMD for the most part. But unless you need the hyperthreading, go with an i5 if you switch.