It is not a great deal of wires to justify bi-modes i'd say. If they went via chat moss then maybe. But those are two quite small sections. 185s or mk5s certainly seem the logical choice.
Agreed. Plus unless the bi-modes can switch sources while in motion they won't be able to use Trafford Park-Oxford Road or Stockport-Hazel Grove.
802s (and 800s) can switch power source in motion. Hopefully now that the DfT have won the legal battle and the Transport Works Act Order has been granted for the Hope Valley passing loops the 3rd express service could start in December 2021. I would favour using 802s as soon as a follow on order can arrive then switch them to the Chat Moss route as soon as Northern can run a Northern Connect service between Liverpool and Sheffield via the CLC.