Not to necessarily delay your resin purchase, but you might want to request a High Temp sample part so you can see how it feels to handle, and how it behaves in your heated environment with some impact or simulated load.
On the bright side, the decrease in stiffness, or heat-softening, that leads to slumping and deflection at high temperatures, also corresponds to an increase in toughness and resilience at those temperatures.
Rigid and Grey Pro resins also have higher heat deflection temperatures than our other resins, but not above 80C like High Temp. Also, High Temp will be about as brittle as it can get after you finish post-curing it, but you may want to consider giving your parts a coat of automotive spray enamel or something to block further embrittlement from the UV you mentioned.
I can’t speak to whether a polycarbonate-like resin will be possible in the future or not, but it would at least be closer to our current range of properties than a mythical PEEK or Ultem-like resins some users hope for.