While impractically expensive, the escapement parts from the C07.611 could be swapped straight into a PRX? Better yet, why not just swap the movements completely?

I also subscribe to the idea that if the synthetic escapement was actually better, It would also be found in the C07.611 & C07.811 movements (or perhaps manufacturers are testing the waters on the cheaper movement).

With the C07.1XX movements now being found in over 250 different Tissot & Certina watches (as shown on watchbase.com), I have to imagine these questions are going to start coming up more and more frequently.

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"C07.111 This is used in the lower price range within the Swatch-Group. They use the plastic Escapements. The Balance spring is made of Nivachron. Which is also Antimagnetic (not as much as Silicon I guess but good anyway). This is what Tissot uses in the PRX.

C07.611 This is used in the higher tiers like in Rado-Watches or some Midos. It has steel parts only and the balance spring is also made of Nivachron.

C07.811 This is based on the chronometré movement of the 2824-2 an uses the Silicon(Silicium) balance spring, which you can find for example in the Tissot Gentleman."

- Sourced from @Uhrologe's comment above