Everything in the guitar chain effect your tone. Where you pick, how you pick, pick-ups, guitar wood, guitar structure, guitar settings, amp setting, effects setting. Even the space you are playing in.
Check out these tutorials.

http://www.guitartricks.com/search.php?search.x=17&search.y=10&search=Submit&query=tone

" Is it worth an up grade" if your going for a guitar with better play-ability then you can get from your present guitar, then go for it.

As for your old guitar, save it for experimentation, back up, guest, or some kid that can afford to buy one.
Just my opinion.. Good luck and hope you find the dream guitar.