Very unlikely someone has owned and raced both. Your best bet, I would imagine, would be to search for reviews on the bikes separately, look for trends, read between the lines, and draw your own comparisons.

MXGimp on here had both.

I have a P5D, so can’t answer but the above can.

I'm about to pull the trigger on a SCD. In fairness I've been holding off on a new bike for quite a while now as I'd not seen anything that met the needs I had. Until the SCD.

In fairness then pretty much all the flagship bikes are 'good' and each is better than the others at something - storage, zero yaw aero, high yaw aero, weight, stability, cornering, maintenance/travel breakdown, even aesthetics.

So for me it was a case of thinking what was important to me, then seeing what ticked off all that I wanted, in the order I wanted. So in my case the three standout things for the SCD were stability (my top need), storage and then the bonus was the low weight as I'm thinking in this ownership cycle I'll be doing some hillier races.

That said, I know the P5 is a faster bike in some situations, has more flexibility in terms of bars and there are plenty of storage solutions for it. It's all about your specific needs, something that I find doesn't come through all that often in reviews/owner posts.