Would upgrading to a new guitar make a big difference?

It's all objective, but generally a more expensive guitar will have better pickups. Then again, I know people who will buy a $1500 guitar and immediately change the pickups. It depends what you like. If you're happy with the quality of your guitar, you could always put better pickups in it, that way you can choose based on what sound you want. It may not sound as good as a really expensive guitar with the same pickups, but it should be a major improvement... Look into GFX pickups if you want inexpensive, but good sounding pickups. If you aren't as concerned with price, Seymour Duncan and Dimarzio are popular choices. I've also been impressed with Rio Grande.