The TalkBass community will never try to talk you out of a purchase, only encourage you to spend your hard-earned coin. I don't say that as a dig to anyone who has replied to you. TB is full of great people who take time to offer their sincere advice. I just say that as something you should be aware of when you ask a question like this.
Whether or not you choose to upgrade, do you know how to intonate the bridge? It's a pretty easy thing to do if you have a few simple tools (screwdriver or hex wrench, but probably just a screwdriver) and a tuner. The basic gist of it involves adjusting your string lengths so that they're "in tune" with the fretboard, so that when you play, the bass stays in tune as you move up and down the fretboard. Might be all you need to fix the issues with your Squier.