You will be able to hear the difference between a CHA47 and a META42 with your present PCDP, erikiksaz. You will especially be able to hear the difference between a CHA47 with OPA2132/4 op-amps and a META42 with moderately high-end chips, which you can get for your $200 number.
I also have a Panasonic SL-CT570, and it's my current portable reference. While it is indeed flawed, it's not bad for a portable. One thing to consider is that getting a better amp may help you to hear the problems in this player more clearly.
My current full-size reference CDP is the Music Hall CD-25 ($600 street). While it does sound better than the Panasonic, it's not 6x better to match the cost difference.
Spending just $200 on a full-size player probably won't give enough benefit to be worthwhile. Keep in mind, that's not much more than $100 over the cost of your PCDP, a difference that's probably completely going to cover the larger enclosure, the "real" power supply, the larger display, the remote control, and the larger I/O jacks. Kelly's idea on DVD players might have some merit, though: if you bought a good DVD player with a 96 or 192 kHz DAC, you might get a worthwhile sound improvement, and even if you didn't, you'd at least have a good DVD player so your purchase wouldn't be a complete washout. Also, you could always add an outboard DAC later if you wanted.
Keep in mind, I'm biased on the META42 issue, since I've got a stake in the META42 -- but unless you can raise that $200 spending limit, I would say you'd get a bigger bang from an amp upgrade. At the same time, setting your sights a little higher and getting a better source is also a good idea. Remember, once the signal is analog, everything you do to it is damage in some sense of the word. Better to start with a good signal than to try and fix it after it's been damaged.