For a sequence of choices, is it better to ask all on one page, or break them up into seperate steps?

A customer is buying a medical product. During the checkout process, she's configuring the product. She has two configuration choices to make:

  1. The physical unit that the product uses (choose from 2 options)
  2. The UI language of the product (choose from 2 options)

This is in the context of a ~10 step process from choosing the product -> configuration -> shipment info -> payment info -> overview -> checkout. There might be more configuration steps in the future, but for now there's only 2.

I can show both configuration choices on the same screen, or break them up to have one screen for each choice. Both approaches have their own advantages:

Advantages to having both on one screen:

  • Fewer steps
  • Checkout flow bread crumbs don't have to change (there's only one "Product configuration" step)

Advantage to having a separate step for each choice:

  • Fewer things to understand on a screen

Questions:

  • Do you have tips for this particular issue?
  • Are there studies or best practices on reducing the number of choices per screen?