The disagg hook in the Python suite could be enhanced to take a parameter that does switching between leader and follower mode.  Some notes:

• mostly, we like our Python test to be consistent - so we probably need to pick predictable times to do a switch (e.g. after the Nth API call, where the next N is chosen using a RNG with a known seed).
• That said, it would be nice to run it (or some portion of the tests) with a "random" seed - any failures should be reported along with the seed used.
• Since a checkpoint on a follower has no effect, and tests might look for an effect, we might need to force switch to leader when a checkpoint is called.  Checkpoints in a different thread, or any multithreaded activity will probably not work "predictably".
• The hardest part may be triage.  First identifying tests that run (maybe use hook_disagg_switch.fail similar to hook_disagg.fail).  How much time to we spend trying to triage the failures?
• Even with the last point, it will probably be worth it, esp if we find crash/asserts that we might not otherwise locate.