Turntable Upgrade Help

I have a question about listening to records on my system.  I'm pretty happy with what I have, but I'm wondering if I'm missing something. I have a Cambridge Audio Azur 651R AV Receiver. I have a pair of Quad 23L speakers. My phonostage is a vintage Yamaha C-4 that has been cleaned and recapped. My turntable is an MMF-5 with a Goldring 1042 cartridge with less than 50 hours on it. My big question is about the turntable. Like I said, I like the way that everything sounds, but because this was my first foray into higher quality stereo equipment, I don't have anything with which to compare it. If I upgraded to a Marantz TT15 or something in the 1500 dollar range, would I hear drastic improvements? I look for bargains on some of the dealer markets to get higher end equipment that has been discounted into this price range. As an example, I was just a little late pulling the trigger on a Gold Note Valore 425 SE, which retails around 2000 USD. Would that have made a big difference in sound compared to my MMF? Is there something else in my system that might be a weaker link. I just don't know because I haven't heard anything else.

Thanks,

Jim