OP
your question is would a Rega P3 improve over a Technics Direct Drive.
I once owned a Rega P5. They sold with an extra box that was supposed to guarantee speed stability. I should have asked myself why they needed a separate box to cure a problem that they couldn’t fix with the base table. With or without the box, it had terrible speed instability issues, particularly at end of side. I had a record that had the first movement of Beethoven’s Moonlight Sonata at the end of side one. The famous piano triplets were so distorted that they sounded like an ondes martinot. The same lp sounds superb with my Technics Direct Drive.
I notice that reviews, particularly UK reviews, of Rega tables seem to spend a lot of time reproducing Rega measurements claiming they have solved speed instability issues. One wonders why they doth protest so much…I simply will never invest again in a Rega table. Fool me once…