I've had a Pro-ject Debut II turntable for almost 11 years now and have largely been satisfied with its sound. However as the rest of my kit has improved its flaws have become more noticeable.
In particular, there is a noticeable rumble on some records and I wonder whether it would be advantageous to change the platter from the supplied metal one to acrylic.
Alternatively, I have considered that it may be time to move up to a more expensive turntable such as the Rega P3 or Pro-ject RPM 5. Clearly, I don't want to be spending hundreds of pounds just for the sake of it but wonder what advice you might be able to offer.