Upgrades for Rega P3. Worth it?

Good afternoon, all. Have been considering various upgrades to my Rega P3 and wondering if anyone could share their own experiences with this. In particular, looking for real advice on whether certain upgrades were worthwhile and/or had an observable benefit to sound quality to people who've done them.

I currently have a P3 with an Ortofon 2M Blue cartridge, Clearaudio counterweight, and Pro-ject Tube Box SE II phono stage. Potential upgrades I have considered:
Rega TT PSU power supply,
Groovetracer (or other) subplatter,
Groovetracer (or other) acrylic platter (vs. stock glass),
Phono cartridge replacement

Are any of these really worth doing?